Group 29 - Kona Shred Mountain Bike

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Kona shred.jpg

Contents

Summary

For our project we disassembled, analyzed, and re-assembled a 2005 Kona Shred bicycle. This included the free wheel assembly, the brake calipers, shifters, the drivetrain, and the derailleurs. We initially intended on analyzing the inner working of the suspension, but we were unable to acquire the proper tools necessary for the dissection.

Management

Overall, our group struggled with procrastination and workload. On multiple occasions, the project was left until the last minute and completed by one or two members. Each week we seemed to progress and work on this, however, by the end of the project we still have not been able to work efficiently.

Disassembly

During our disassembly, we weren't really sure of what each part did. We also did not do a good job of storing our parts in a way that would be conducive to the reassembly. Overall, we only had a few minor problems with the disassembly. We had to cut the brake lines in order to remove them, and could not reuse them. We had to order a special tool to remove the crank arm, and needed to use compressed air to remove the handlebar grips. We also did not do a very good job of originally documenting it and had to go back and take more pictures of our parts and refer to pictures for the process we used. Unfortunately, we were not able to dissect the suspension because we couldn't obtain the part used to disassemble it because they are only sold to manufacturers and bike repair shops.

The majority of us thought that the bike would be quite simple and easy to analyze. At an overall level it is quite simple, with the pedals driving the bike, the brake handles to slow it down, and the shifters to change gears. However, when these sub-systems and individual components were analyzed, we saw how complex they are. Each subsystem contained around 20 components each. When disassembling the bicycle, we realized how many parts there were but did not quite understand how complex they were, and what they all did. After analysis, we had a better idea.

Analysis

After analyzing the bicycle, we had a much better understanding of what each part did. We were able to see how the shifters caused the derailleur to move, and force the chain to change gears. We were able to understand how the free-wheel allows riders to continue to ride without pedaling. We took apart the entire brake caliper, and created a complete 3D model in SolidWorks©. Lastly, we were able to understand why each component was mounted in it's place.

Assembly

As stated before, we did not do a very good job of storing our parts. We spent the majority of the time assembling the bike on figuring out which screw went where, and fixing mistakes we made. Each part took longer to assemble than to disassemble. Although it was more difficult than the disassembly, it was still somewhat simple, but time consuming. For most of the components, we were able to follow our disassembly steps in reverse. However, for things such as the brakes, we were not able to assemble them because we had to destroy the part. Many things had to be done in the proper order because of the placement, and we learned this the hard way. Multiple times we screwed something in, only to realize that another piece had to be screwed in, or we mounted the shifters before the brake handles when they had to be opposite. Fortunately, considering the overall durability of the parts, we did not break anything during our assembly.


Gate One

In this gate, we will propose our plans for the dissection, group assignments, and group meetings. Completeness of this gate will help the rest of the project run smoothly and easily.

Work Proposal

This section explains the initial plan for the reverse engineering of the 2005 Kona Shred we have selected as our product. First, we will list the tooling we have determined to be required. Consequently, we will discuss our plan for disassembly.

Disassembly Process

Below is our proposed order of disassembly as well as the tools used for each step. Our plan for analysis entails breaking the bike into subsystems and then treating each of those as a standalone product. We will begin where normal usage ends, the frame with the wheels removed. For sake of clarity we have listed each step, with the expected procedure and required tooling below.

Required Tools

As of Oct 9 this is our best estimation of the tools we will require in order to properly disassemble the bike.

Metric Hex Keys:

2-10mm

Adjustable wrench
Metric Wrenches:

6-15mm

Screwdrivers:

0, 2 Philips
.25" Straight

Shimano Free Hub Locking tool
Shimano Bottom Bracket tool

Disassembly

1. Cable Disconnection

a. Loosen Clamps, 4: Hex keys

2. Derailleur/Shifter Removal

Shifter

a. Remove Screws, 7: Hex keys





3. Disc Brake Caliper/Lever Removal

a. Remove Screws, 8: Hex keys

4. Front Fork Removal

a. Remove Handle Bars:
i. Remove Screws, 4: Hex keys
b. Loosen Headset Nut, 2: Wrenchs

5. Bottom Bracket Removal

a. Remove BB: Shimano BB tool and Wrench

6. Free Wheel Disassembly:

Brake Caliper

a. Remove Lock-ring: Shimano Lock-ring tool
b. Loosen Lock Nut: Wrenchs






7. Disc Brake Caliper/Lever Disassembly

a. Remove screws, 4 per caliper: Hex keys
b. Remove screws, 3 per lever: Hex keys

8. Derailleur/Shifter Dissassembly

Derailleur

a. Remove Screws, 3 per derailleur: Hex keys
b. Remove screws. 3 per shifter: Hex keys






Due to the intended serviceability of bicycles and past experience, we estimate that it should take under one hour to disassemble the bike into individual components. Disassembling each of the components should only take around half an hour, however this estimate may be off due to the unknown complexity of some of the internal systems, of these we view the following to be the most complex: freehub, disk brake calipers and the shifters. We came to this conclusion based upon the presence of enlosures. In order to assure that the product is put back together in the proper manner with little to no damage made to its functionality, we will document the disassembly process by taking pictures of each step and writing a brief paragraph explaining any challenges faced along the way.

Reassembly

Since everything is easily removed, we expect that everything will be just as easily replaced. To assemble the bicycle back together, we will simply reverse our disassembly process. This should require the same amount of tools, and slightly longer than the disasembly process.

Management Proposal

Weekly Meetings

Group management will be a very important job for this project, mainly because most of us are prone to procrastination. Our group will plan to meet roughly 3 times a week. Every Monday at 5:00pm we plan to meet for a brief period of time, usually 30 minutes to an hour. We will meet in the second floor of Knox, unless otherwise stated. The purpose of these meetings will be mainly to outline and plan our course of action for the week. Our next meeting will be to get some hands on time with our product. These meetings will always be some time during the week, at 5:00pm on Wednesday or Friday at the SAE lab. These meetings should be slightly longer, generally lasting an hour or two depending on how much work needs to be done. The third weekly meeting will be on Sunday, and will occur via the Internet using Google Documents to edit and write up our progress. If necessary, more meetings may be scheduled to keep up with the project deadlines. It is expected that not every group member will be able to attend every meeting, but we will all do our best to free up enough time to meet at least once or twice a week. If a particular group member misses too many meetings, Scott Godfrey, our Group Liaison will accept the responsibility of resolving the situation. As the Group Liaison, Scott will also be responsible for any necessary communication with the class instructors.

Point of Contact

Scott Godfrey, our Group Liaison will be appointed as our point of contact. This will involve contact not only between the group and the class instructors, but also between other group members.

Proposed Schedule

Brief overview of our projected project deadlines. As our group makes progress in each gate, the progress will be noted on the Gantt Chart.
























Group Abilities

Group Member Strengths Shortcomings What to Develop
Scott Godfrey Basic CAD experience.
Quick learner.
Good with tools.
Hard worker.
Heavy procrastinator.
Not much HTML experience.
Time management.
Kyle Devine Basic CAD experience.
Proficient with Microsoft Office.
Possess leadership abilities.
Not much web page experience.
Not much experience with mechanical products.
Work planning.
Kishen Das Bicycle enthusiast.
Has built own bike.
Proficient with DDS SolidWorks.
Prone to procrastination.
No HTML experience.
Work planning
Andrew Dorman CAD experience.
Excellent writer.
Proficient with Microsoft Office.
Quick learner.
Willing to follow instructions.
Distracted easily. Time management.
Lance Brouker Good planner.
CAD experience.
Proficient with Microsoft Office.
Work well under pressure.
Poor technical writing skills. HTML coding.

Group Jobs

From the previously stated group skills, we have devised the following jobs and tasks associated with those jobs.

Group Member Job Title Responsibilities
Scott Godfrey Group Liaison Ensure communication between group and instructors.
Resolve group conflicts.
Kyle Devine Project Manager Assign tasks to group members.
Ensure fair and equal workloads.
Kishen Das Technical Expert Oversee dissection of bicycle.
Recreate components in SolidWorks program.
Lance Brouker Project Organizer Manage group meetings.
Ensure timely completion of tasks.
Andrew Dorman Chief Editor Check for grammatical and spelling mistakes.
Ensure writing professionalism.

Product Archaeology

Without actually physically taking apart our product, we were still able to assess and analyze our product to a certain degree, and provide an initial idea of how our Kona Shred bicycle works.

Development Profile

The Kona Shred bike we are working on was developed in 2005. At the time of its development there were rapidly growing global concerns over the excess production of green house gases that was occurring all over the world. In the United States there were many economic concerns over the rising fuel prices and the early signs that the economy was beginning to decline. Due to these economic and global concerns the developers of the Shred series focus became offering both experienced riders and newcomers a thoughtful, reliable, and well balanced mountain bike at an affordable price to riders all over the world. Kona is based out of Vancouver, BC and Ferndale, Washington and their bikes are sold in stores internationally. Currently they have partnerships with bike parks in countries such as Italy, the United Kingdom, the Czech Republic, and Austria.

Usage Profile

Quite simply the products intended use is to be ridden. Whether it is ridden as a alternate cost effective mode of transportation, competition, or just for recreational use is up to the owner. It can be used on multiple terrains and it works well in inclement weather. The 2005 Kona Shred is best suited for a budding enthusiast. Professionals may own one but they would most likely not use it at any events because they would compete with more customized high performance bikes that are better equipped to help them win; whereas the Kona Shred is built more for beginners. In essence the job of the 2005 Kona Shred is to not only provide transportation but also an enjoyable riding experience to its owner.

Energy Profile

Our product, the Kona Shred, requires the riders to provide the energy needed to power the bicycle. The initial mechanical energy provided comes from the rider themselves using their legs to turn the pedals. This energy is then carried to the sprocket then through the chain and down to the gear train, as translational mechanical energy. After this, the energy is then transferred from the rotating gears into the tires themselves, which in turn will move the bicycle forward. The main method of importing energy into the system comes from the work done by the rider. However, there are other ways that the bicycle will import energy, one if which is through the change of potential energy to kinetic energy. Should the bike be traveling downhill, the potential energy due to its height will be transferred into the system and seen as an increase in speed. Due to the nature of our product, there is no other transformation of energy beyond the changing of potential energy to kinetic energy and vice versa. As is the case with nearly all bicycles, there are no engines or motors involved in them that would be the cause for a transformation of energies from one type to another. Since there is no transformation of energies, there is also the benefit of not losing any energy during the exchanges. Any type of power transformation involves a minimal loss of energy, which is avoided in the case of our bicycle, leading to a higher efficiency of the energy use. Another key part of the energy profile is the absorption of the mechanical energy caused by bumps in the surface or by taking the bicycle over jumps, as it is designed for. Once this vertical translational energy enters the system, the suspension must work to dampen it and steady the bike once again. While we are not quite certain as to how it accomplishes this task yet, we will look more deeply into it once our product dissection begins.

Complexity Profile

The Shred, like most modern bikes is an amalgamation of componentry, with the manufacturer only making the frame and other non-moving parts. The actual componentry on the bike is made by other companies, in this case, Marzocchi and Shimano. By the numbers the bike, excluding the frame, has 4 main component groups each comprised of 4-6 visible parts, for a total of around 24 components, excluding any fasteners. The components then again comprised of sub componentry, as well as screws and bearings. Most of the components do not consist of complex parts and part interactions, as they need to be easily serviceable. All of the connections and interactions between the product components are simple mechanical processes such as energy conversions and the transport of work. The enclosed part are difficult to service due to the casing that protects the internals from dirt and damage, which in turn indicates more complex interactions.

In the drivetrain system we have identified the following components:
2 derailleurs, each comprised of 3 linkages, a spring and a sprocket.
1 Free Hub, comprised of bearings and a ratchet system.
10 chainrings.

The braking system contains the following:
2 calipers, comprised a housing, piston and we suspect a spring.
2 levers, comprised of a housing and a lever.

The suspension fork has a twin shock setup:
Oil Shock, comprised of a twin springs damped with an oil piston.

All user controllable components are mechanically actuated. The general form of this is the Bowden cable, the name for the housed cable seen in pull type applications; This is the form of actuation for the derailleurs and the brakes. In the end all the systems interact though the wheels which is very simple. The brake calipers compress pads onto the disc which slow the bike down via friction; and the gear train transmits power through the freehub.

Material Profile

One of the key aspects of any bicycle is its ease and simplicity of being taken apart and reassembled. For this reason, most of the materials that are contained within the bike are visible without much disassembly. The largest part of the Kona Shred, the frame, is made of aluminum and is held together by joint welds throughout the frame. The next component that can be seen without taking apart any components is the front fork. This is also made entirely out of aluminum as it is a strong, yet very sturdy material that is ideal for the desired purpose of this bike. Next, we can take a look at the wheels and rims themselves. As is the standard objective for bikes of this type, light yet strong materials are needed, especially when it is intended to be used as a freestyle bicycle as well. The spokes that support the wheels themselves are made up of two millimeter diameter stainless steel pieces. The handlebars themselves are made of aluminum, with the grips being made of rubber. The seat appears to be made of a canvas material similar to leather. The pedals are made of aluminum to decrease weight. The chain is made of steel because strength in the chain is paramount. Components such as screws, and mounts appear to be made of steel. Lastly, as with most bikes the tires are standard rubber tires to allow for them to be switched out rather easily.

In addition to the components that are clearly visible without any dissection of the bicycle, it is important to take note of the materials and components we can not see. The most simple of these materials would be the braking system. Since the Kona Shred employs a disc braking system, it requires a turning screw to engage the brakes onto the disc, which in turn slows down the rotation of the wheels. Also, there is a cable that runs from the handbrakes at the top of the handlebars down to the front and rear forks that engage the system. When looking at the suspension system, it is clear that there are a number of materials involved that help to dampen the force of landings and any bumps in the riding surface. From our initial assessment, we believe there is some type of fluid and piston combination within the suspension that helps reduce these forces, and will look further into it during our product dissection. Lastly, the freewheel is another component that we are unable to see without taking apart the product. We can assume that there is some type of gear mechanism that is only engaged when the rider is pedaling the bike.

User Interaction Profile

Since the only form of power for the Kona Shred comes from the user themselves, the user interface with the product is vital to it. Not only is the rider responsible for providing the energy needed to use the bike, but the rider is also responsible for full control over the Kona Shred. For example, it is the riders job to also steer the bike, change the gear system to the rider’s preference while riding, and to slow the bike down to avoid collisions and crashes with various obstacles.

There are two main ways that the bike can be controlled and steered in the desired direction. The simplest way to accomplish this is to simply turn the handlebars in the direction the rider wishes the bicycle to be turned. The main downfall to this method of controlling the bike is that dangers arise when the rider is traveling at high speeds. Turning the wheel at too sharp an angle can cause the bike to stop short and cause and lead to crashes. Alternatively, the rider can slightly lean to the side they wish to turn in and allow their weight to slowly turn the bicycle in that direction. This leads to a much lower risk of crashing and injury to the rider. In addition, the rider must change gears within the gear train, depending on the circumstances of the surroundings they are riding in. In most cases, when traveling uphill at low speeds it is suggested that the bike be set to a lower gear to assist in climbing. Conversely, while traveling on flat grounds at higher speeds, using a higher gear would make keeping that speed much easier. The controls for the gear train are located towards the middle of the handlebars. Another part of the product-rider interface that is key to the products usage is for the rider to control the speed of the bicycle. While pedaling will obviously increase the rider’s speed, grabbing the brakes at the front of the handlebars will allow the bike to slow down at a reasonable rate. These previously mentioned methods of interaction with the bicycle are not too intuitive in the sense of their complexity, but their location on the product itself allows for complete control of all systems at the same time.

Since the pedals require the use of the rider’s legs, turning requires turning the handlebars or leaning, and the brakes and gear shifters are located right around the handlebars, the rider has the capability of controlling all aspects of the user interface at nearly the same time. The product is generally easy to use, assuming the rider has previously learned to ride a bicycle. There is not much difference from most bikes to the Kona Shred which makes using it, even for the first few times, relatively simple. The main difficulty in riding the bike comes when the rider attempts to use it in the other manner it was designed for, as a dirt jumping and freestyle bike. In order to keep the product working in the manner it was designed for, a small amount of regular maintenance is required. There are a few problems that arise during the course of using the product that are simple to fix such as the chain falling off the gear train and fixing a flat tire. Both of these can be remedied with a few wrenches and do not require a great deal of money to be spent on replacement parts. In addition it is helpful to grease the wheels and gears once in a while to minimize the friction between parts and ensure that they hold up to the daily wear and tear of riding the bicycle. However, since our bicycle uses disc brakes they would need to be repaired more often than other types of braking systems found on similar bikes. Of the regular maintenance that is required with our product, this would be the most intensive, yet could still be done by the rider themselves, as long as they have the proper tools.

Product Alternative Profile

As a mode of transportation, there are multiple alternatives to the Kona Shred bicycle. These alternatives include personal vehicles such as a car or truck, public transportation such as buses or trains, and other methods originally related to action sports, such as skateboards, long-boards, roller blades, and scooters. And of course, you have the good old fashioned method of walking. Below is our comparisons between them.

Alternative.png

From the table we have created, it is clear that the Kona Shred bicycle is not really the best for any of our categories, but it is not the worst. Cars and gas powered vehicles are much more expensive, while other methods are slower. The Kona Shred is somewhere in the middle for each of the categories. However, the Kona Shred has another use other than just transportation. It can be used for riding up mountainous terrain, and jumping dirt ramps.

References

http://store.sector9.com/Default.aspx?cat1=COMPLETES
http://metro.nfta.com/Routes/Fares.aspx
http://www.bikepedia.com/quickbike/BikeSpecs.aspx?Year=2005&Brand=Kona&Model=Shred&Type=bike

Gate 2

In Gate 2, we performed the physical dissection of our Kona Shred bicycle. We documented each step with written notes as well as pictures. We will analyze our dissection, as well as any conflicts we had with our dissection, or with our group.

Project Management: Preliminary Project Review (Cause for Corrective Action)

Management Proposal

Our management proposal worked when it was followed. The first couple weeks after Gate 2 was assigned, we failed to meet and set up exact dates. Given that we are all very busy, it is hard for us to set up meetings to begin with, and unless we make an effort to, setting up meetings proves to be a challenge. We also had some miscommunication when setting up meeting times for the initial dissection. After we were finally able to set up, and follow a meeting date, we began to follow the management proposal more routinely. We were able to set up meeting times for the last couple weeks when they were necessary. We were also able to work our a group plan of action on when and how we would complete the Gate, and Assignment 6. In particular, meeting on Mondays were fairly easy to schedule, but the second meeting was harder to commit to. Our proposed Sunday meetings on Google Documents worked fairly well, but had complications. It works when we have a plan of action laid out prior to the meeting, whereas it did not work very well when we didn’t. The workload did not divide evenly, and did not get done in a timely manner. This relates back to our assigned group jobs and our inability to follow them effectively.

Group Jobs

When it came to effectively completing our assigned Group Jobs, we have generally failed to do so. It seems to be harder to follow these jobs than first expected. For the most part it seems that when one of us sees that something needs to be done that would normally fall under jurisdiction of another group member, they go ahead and do it themselves. For example if one person feels that we need a meeting, they schedule it even if it isn’t their job. This applies to other things such as emailing the instructors with questions, and editing the assignments. And while there isn’t a problem with this, it should be noted that the group jobs are generally hard to follow because we all try to do a little of each, and that seems to be working okay for us.

Work Proposal

Our Work Proposal also had a few conflicts arise during the dissection. To begin, we ran into a minor challenge when disconnecting the cables. We thought that we would simply have to loosen the nuts with an Allen wrench. However, when it came to removing them, we were forced to cut the end of the wire off because there was a clip attached to the end that was not easily removed. This is likely because cables are cheap enough where they are meant to be replaced rather than repaired. When taking off the shifters, we originally did not plan on having to take off the handlebar grips, but ended up having to. This did not seem to be a major problem, but turned out we could not remove them with our hands. We needed to use compressed air to loosen them off of the bars. We were very lucky that we had this at our disposal. Again, when removing the shifters from the handlebars, we ran into another problem. Since the bike has been previously used, the ends of the handlebars were scratched up and bent, and the shifters could not be removed right away. We had to sand them down so they were smooth enough to slide off the shifters. We also ran into a few problems when removing the pedal system. First, we spent some extra time trying to remove the left pedal. The problem was that the left pedal is threaded oppositely so that it doesn’t unscrew when being used. We also were not able to remove the crank shafts after the pedals were removed. This is because they are not made to be removed without a specialized tool. Once we were able to acquire the tool, we removed them in our second dissection meeting. When trying to removing the front fork, we were unsure how exactly to go about it. We originally had planned to remove it by loosening a nut. However, this did not work. After looking it up on the Internet, we learned that we simply needed to use force, and we ended up hitting it with a hammer and removing it. Lastly, we had originally planned on removing the bearings, but realized that they are not meant to be removed without destroying them.

Due to the complexity of the brake calipers and the shifters, we were not able to plan out a dissection of those specifically without taking them apart. However, we were able to take them apart and documented them in the tables below.

Unfortunately, we were unable to dissect the suspension as originally planned. We were unable to acquire the tool to take it apart. We had initially thought that we would be able to purchase the tool and dissect it. However, when we went to purchase the tool, we found out that it is only sold to bicycle repair shops directly from the manufacturer. We will continue to look for a way to acquire this tool, or at the very least have a bicycle repair shop take it apart, or find a dissection online.

Product Archaeology: Product Dissection

Difficulty Scale

During our dis-assembly process there was clearly a difference in difficulty for removing different parts of the bicycle. However, we needed a way to quantify these differences. So, to show these differences, our group decided to create a Likert scale from one to five, with five being the most difficult. In our particular scale, we used three different categories to quantify the difficulty of each step, number of tools required, time required, and people required. The difficulty can be determined by the highest corresponding difficulty of either of the three categories in the following table.

Difficulty Tools Required Time Required People Required
1 1 or less Less than 2 minutes 1
2 2 or more 2-4 minutes 1
3 2 or more 5-6 minutes 2
4 3 or more More than 6 minutes 2
5 Any specialized tools
ex) Air compressor
Not able to complete 3 or more


Dissection Documentation

Sub-System Removal

Step Task Tools Actions Difficulty Picture(If Necessary)
1 Disconnect Cables 5mm hex, 9mm crescent, wire cutters Cut off cable end-caps. Remove screws or nuts securing cables. 4 Cables.jpeg
2 Remove Wheels Hands Release quick releases and remove wheels. 1 Wheels Off.jpeg
3 Remove Disc Brake Calipers (2) 5mm hex Remove screws that fasten calipers to frame. 2 Brake Calipers.jpeg
4 Remove Rear Derailleur 5mm hex Remove screw 1 Derailleur Removal.jpeg
5 Remove Front Derailleur 5mm hex Loosen screw clamp 1
6 Remove Pedals 14mm crescent Remove right pedal by turning counter-clockwise, left pedal by turning clockwise 3 Pedal Removal.jpeg
7 Remove Crank Arms 10mm hex, special crank arm puller Remove cap screws, use puller to lift out cranks 5
8 Remove Hand Grips Compressed air blower Insert nozzle between grip and handlebar, blow air while pulling grip 5 Grip Removal.jpeg
9 Remove Brake and Shifter Levers 5mm hex Loosen clamp screws, slide off 2 Shifter Removal.jpeg
10 Remove Handle Bars 5mm hex Remove screws on stem. Loosen screws clamping stem to fork. 1 Handlebars Removal.jpeg
11 Remove Stem 15mm crescent Remove fork cap. Lift stem and spacer out 1
12 Remove Fork Rubber mallet Tap top of fork with mallet. Fork should then slide out. 3 Fork Removal.jpeg
13 Remove Bottom Bracket Park tool BB-19 Loosen the end caps and remove ball-bearing 5















































































Brake Caliper Dissection

Step Task Tools Actions Difficulty Picture(If Necessary)
1 Remove Brake Pads Needle-nose pliers Remove cotter pin with pliers, slide out pads 3 Brake Pads.jpeg
2 Remove Pad Support 5mm hex Remove the screws holding it to main body 1
3 Remove Dust Cap #0 Philips Remove screws 1
4 Remove Preset Adjuster Hands Pull adjuster out 1
5 Remove Spring 12mm crescent Remove the nut. Slowly release spring-loaded cap. 4
6 Remove Piston Hands Push the piston out of caliper. Collect internal bearings. 3 Brakes Final.jpeg



























Brake Lever Dissection

Step Task Tools Actions Difficulty Picture(If Necessary)
1 Remove Tension Adjuster Hands Unscrew 1
2 Remove Lever From Body Punch and press Press out pin 5 Brake Lever Final.jpeg













Rear Derailleur Dissection

Step Task Tools Actions Difficulty Picture(If Necessary)
1 Remove Cable Adjuster Hands Unscrew from body 1
2 Remove Limit Screws (2) #0 Philips Unscrew from body 1 RD Chain.jpeg
3 Remove Tension Pulley 3mm hex Unscrew bolt. Slide out pulley 3
4 Remove Guide Pulley 3mm hex Unscrew bolt. Pulley and back-plate should be free. 3
5 Remove Swing Tensioner Small Screw Driver Remove C-clip, bolt, torsion spring, and pre-tensioner 4 Rear Derailleur Final.jpeg


























Free Hub Dissection

Step Task Tools Actions Difficulty Picture(If Necessary)
1 Remove Quick-Release Hands Unscrew end-cap, slide out 1
2 Remove Lock-Ring Lock-Ring tool Hold the cassette, unscrew the lock-ring with tool, slide off cassette 5
3 Remove axle 14mm, 15mm wrench Remove both nuts on the brake side. Pull out axle, collect ball bearings. 4
4 Remove Free Wheel 10mm hex Insert hex wrench into free wheel side. Loosen free wheel. 3 Free Hub.jpeg
















Removal Intentions

Since bikes are made to accept many different variations of parts, most are designed to be taken apart to be repaired or maintained. However, not all of them are meant to be repaired.

Sub-System Removal

Disconnect Cables – The cables were not meant to be taken apart, unless they are being replaced. The only way for them to be removed is to cut off the caps, which leaves frayed cables in the open.
Wheels – These wheels are made to be taken apart as it required no tools to do so and is necessary to fit the bike into cars and other small spaces.
Disc Brake Calipers – Brakes are supposed to be taken apart since only a hex wrench was needed to get them loose.
Derailleurs – Both derailleurs are made to be taken off as they need to be serviced and required minimal effort and tools. They were also easily reached.
Pedals – These are not meant to be taken apart regularly as they required more complex tools than the other parts and can only be replaced since they’re made of one solid piece.
Crank Arms – These were not meant to be taken apart as they required tools that are not found in most bicycle shops and required a great deal of force.
Hand Grips – The grips are meant to be taken off as it is necessary to take them off for the removal of numerous other parts.
Brake and Shifter Levers – Made to be taken apart since they came off easily with simple tools and are needed to be removed for other parts to be removed as well.
Handlebars – The handlebars are supposed to be removed as they only required a hex wrench and minimal effort to take apart.
Stem – This is also made to be taken apart due to its ease of removal.
Fork – The fork is made to be taken apart as well since only a simple rubber mallet is needed to remove it.
Bottom Bracket – The bottom bracket is also not meant to be taken apart as it requires certain pieces to be remo
ved that are permanently attached. Once this part is removed it can’t be attached again and must be replaced.

Brake Caliper Dissection

Brake Pads – Removal of the brake pads is meant to be relatively simple as they need to be regularly replaced, just like those of a car.
Pad Support – Since only screws hold it together, which is a type of non-permanent fastener; they are made to be taken apart and replaced.
Dust Cap – Like the pad supports, the screws show that they are supposed to be taken apart.
Preset Adjuster – This part should be able to be removed based on the ease of removal during our product dissection.
Spring – These small parts are meant to be taken apart but only to be replaced by a new part due to defects or breakage.
Piston – Did not require any outside tools which signifies that it is most likely designed to be removed and serviced.

Brake Lever Dissection

Tension Adjuster – Easily removed with just our hands and thus shows it is designed to be taken apart and replaced.
Remove Lever from Body – Typically the brake levers are designed to be replaced as a whole system and not from each other part in the system.

Derailleur Dissection

Cable Adjuster – Easily removed with hands and is needed to be removed to work on the rest of the derailleur.
Limit Screws - The screws are just fasteners meant to be taken apart for servicing.
Tension Pulley – With the hex wrench, the tension pulley easily came apart as it was designed to.
Guide Pulley – The guide pulley is not meant to be taken apart regularly as there are many other parts held in place by it.
Swing Tensioner – Due to the more complex tools and the various consequences of removing the tensioner, it is clear it was not meant to be taken apart for services.

Free-Hub Dissection

Quick-Release – Since the screw can be taken off by hand, it is clear that it is meant to be removed with ease.
Lock-Ring – The free hub itself is not made to be taken apart and dissected as a bike owner and as a result of the complex tools needed it is clearly not designed to be removed.
Axle – Although not as difficult as the lock ring, the axle is also not made to be removed from the free hub.
Free Wheel – Again, even though it is once again easier to take apart than the previous part, the intention of the free hub is to remain as one main component.

Sub-System Connections

Since the sub-systems of the bicycle sometimes need to interact with each other, most of them are connected to the others. To begin, all of the sub-systems are physically attached to the frame of the bicycle. These sub-systems include the free-hub, the drive-train, the braking system, the shifting system, and the suspension. Since the systems are meant to be maintained regularly, they are connected to the frame with non-permanent fasteners such as screws and bolts.

The braking system is attached to the frame at multiple locations. The braking levers are attached with clamps on either side of the handlebars, and the disc brakes are connected to the wheel on the same bolt. This is so that when the levers are triggered, the cable forces the calipers onto the discs. Since the discs are attached to the wheels, when the calipers slow down the discs, they will also slow down the wheels, and the bike. One could say that these are connected through energy, since the rotational energy or the disc brakes is directly related to that of the wheels. When the bike is going faster than desired, the connection from the disc brake to the wheel is very important.

The shifting system is connected only to the frame and to the drive-train. The shifters are connected by clamps on either side of the handlebars, similar to the braking system. When triggered, the shifters pull a cable which move the front or rear derailleur, depending on which shifter is triggered. These derailleurs are connected to the drive-train at the chain. When the derailleurs move, the translational energy is transferred to the chain, and forces the chain onto the appropriate gear. When the bike increases or decreases speed, or if the bike is being ridden on an incline, the connection from the shifters to the drive-train will be used much more frequently.

The drive-train is the most inter-connected of all the sub-systems. The drive train is connected to the frame at the pedals. The pedals are connected to a gear system, which is connected to a rear gear system by the chain. This gear system is connected to the rear wheel, and the free-hub. The chain is also connected to the shifter, as previously stated. The drive-train is used to transfer energy from the user to the rear wheel, and thus powering the bike. Energy is transferred from the pedals, to the front gear system, to the rear system through the chain, and then to the rear wheel.

The suspension is the one system only connected to the frame. This is because it does not interact with any of the other systems. The suspension must only be attached to the frame and wheel so that it can store the energy from the wheels, and release it slowly to the rest of the frame. If the bike is being used on bumpy terrain, the connection from the suspension to the frame is used to make the ride feel more smooth.

The free-hub is attached at the rear wheel, and is also physically attached to the rear gear system of the drive-train. This must be attached to the gears so that when the gears stop moving, the free-hub allows the wheel to continue to rotate freely. If the bicycle is being used to travel long distances, the rider may take more breaks between pedalling intervals, and the free-hub is especially useful.

Although the production and use of the bike as a whole is greatly influenced by global, societal, economic, and environmental factors, the sub-systems are not really influenced by these factors. The materials used to connect the systems such as cables and screws/rivets may be affected by environmental and economic factors, but since it would make such a small impact, this is not seem on our bicycle.

Sub-System Placement

Like most bikes, the sub-systems on our bike are placed strategically so it makes it convenient for the rider to use all of them.

Both the braking and shifting systems are attached on either side of the handlebars. This is because while you are riding a bike, your hands are used to steer, but your fingers can still be used. So the triggers are placed at your fingertips so that you can use these systems without going out of your way. The braking system is also connected at the wheel so it can directly effect the speed, while the shifting system is connected at the chain so it can move it to the proper gear. The drive-train is located lower on the bike so that you can extend your legs while sitting or standing. This is also connected to the wheels so it can effectively transfer your energy. The suspension is attached directly to the front wheel because when the wheel hits the ground, it will transfer that energy directly to your hands. If this energy is large enough, it may cause you to let go, so the suspension is put in between so this does not happen. Lastly, the free-hub is connected directly to the wheel and the gear train. This is so that when the gears stop moving, the rear wheel can continue to move because it is attached to the free-hub.

Although our sub-systems could all theoretically be adjacent to each other, it would make no sense to. They interact with each other, but would not be unusable if they were adjacent to each other. They are connected in the places they are because this makes it easiest for the rider to use the bicycle effectively.

Gate 3

In this gate, we will go into detail about each separate component and subsystems.

Project Management: Coordination Review

Cause for Corrective Action

In previous gates and other assignments, our group struggled to find an even balance of work and scheduling conflicts continued to arise. For gate 3, our main struggle was with finding the time to devote to group meetings and things of that nature. All of us had multiple tests over the past few weeks along with a number of other homework assignments. We were able to meet every Monday and schedule other meetings. We met twice to take pictures of our components and document them. We had agreed to finish our assignment ahead of time to avoid the panic we experienced in the last two gates, but we all failed to do this because of other tests and assignments we were busy with. Procrastination has been our main struggle and is still a problem of ours. For our last gate, it would be beneficial for us to make sure we finish it ahead of time. A good way of doing this may be to have in person meetings where we work on, and finish the gate together.

Product Archaeology: Product Evaluation

Component Summary

Complexity Scale

For our components, it is necessary to create a scale on which we would base the complexity of the each component. Many factors such as component design, geometry, manufacturing process, and component function should be taken into account. Our scale ranges from one to five, with one being the simplest component and five being the most intricate and complex. The characteristics of each level of the scale are as follows:

1 - Component requires one and only one process to be manufactured and has a basic geometric design. Additionally the component performs one simple function in the system.

2 - Component can be made with one or two processes and has slightly involved geometric shapes such as threads. Component performs one, more complex function in the system.

3 - Component must be made with two processes and is more geometrically involved. Component performs two functions or is involved in two systems.

4 - Component is made with three or more standard manufacturing processes or involves geometry that can’t be achieved with these same processes. Component performs multiple functions in different systems.


The complexity rating that will be given to a certain component will be equal to the most complex attribute of the component. For example, if a part only serves one simple function yet must be made with multiple machining processes then the product would recieve a complexity rating of three.

Brake Assembly

Part Number Used Material Manufacturing Process(es) Function Picture(If Necessary) Complexity
Body 1 Aluminum Die Cast, Machined Serves as the main body of the caliper, houses all internals 29 Body.jpeg 4
Dust Cap 1 Plastic Injection Molding Prevents dust and debris from entering internals 29 Piston Cap.jpeg 3
Cable Pull Lever 1 Steel Pressed Provides a mechanism for the cable to gain leverage over the spring 29 Brake cable pull.JPG 3
Piston Body 1 Steel
Brass
Die Cast
Machined
Press-fit
Forged
Presses the pad against the rotor
Allows for adjustment of the initial distance of the pad/ piston via the embedded screw.
29 Preadjust.jpeg 2
Piston Cap 1 Aluminum Die Cast, Machined Ramps along bearing to provide translation of the piston 29 Dust Cap.jpeg 3
Plastic Seal 1 Plastic Injection Molding Keeps dust out of internals 29 plastic seal.jpeg 1
Back Plate 1 Steel Pressed Mount for back pad 29 Rear Pad Support.jpeg 3
Tension Spring 1 Steel Bent Keeps piston away from the rotor when not in use 29 Tension Spring Brake.jpeg 2
Ball Bearings 3 Steel Forged, Polished Allows for lateral movement, along ramps 29 Ball Bearing Small.jpeg 1
C-Clip 1 Steel Forged Retains the pre-adjust screw 29 C-Clip.jpeg 1
Washer 2 Steel Forged Wear surface 29 Brake Washer.jpeg 1
M6 Screw 2 Steel Forged Fastens back plate to main body 29 Piston Screw.jpeg 2
Small Screw 2 Steel Forged Fastens dust cap to cable pull 29 Small Screw.jpeg 2
Nut 1 Steel Forged Secures cable pull to piston cap 29 Release Nut.jpeg 2
Pre-adjust Bolt 1 Steel Die Cast and Machined Allows turning of piston pre-adjust screw 29 M6 Screw.jpeg 2
Rubber Seal 1 Rubber Injection Molding Prevents debris from entering the piston internals 29 Rubber Seal.jpeg 1
Pre-adjust screw 1 Steel Forged Moves the rear pad support back and forth 29 Cable Pulley.jpeg 2
Rear Pad Support 1 Steel Pressed Supports the rear pad 29 Piston Base.jpeg 3
Brake Brackets 2 Aluminum Die Cast Provides the mounting surface for the brakes 29 Brake Bracket.jpeg 2
Mount Cable 1 Steel Drawing Transfers the signal from the brake lever to the screw at brake assembly 29 Mount Cable.jpeg 2
Cable Screws 1 Steel Die Cast and Turned Connects the brake cable to the brake assembly. The torque from the cable closes brake caliper. 29 Cable Screw.jpeg 2
Tighteners 2 Aluminum Die Cast and Machined Adds strength between the brake assembly and the handlebars of the frame. 29 Brake Tightener.jpeg 2
Lever 2 Aluminum Die Cast and Grinded or Milled Inputs the signal of the rider and transfers the force to the brake cable and mount cable. 29 Brake Lever.jpeg 3




























































































































































































Front/Rear Derailleur Assemblies

Part Times Used Material Manufacturing Process Function Picture(If Necessary) Complexity
Derailleur 1 Steel Die Casting, Machining, and Welding The front derailleur moves the chain onto the desired gear 29 Derailleur.jpeg 4
Derailleur Cable Nut 1 Steel Threading The cable nut keeps the cable and derailleur held together 29 Derailleur Cable Nut.jpeg 2
Derailleur Cable Bolt 1 Steel Cold Forged The cable bolt keeps the cable and derailleur attached 29 Derailleur Cable Bolt.jpeg 2
Derailleur Back Plate 1 Steel Compression The back plate connects the derailleur to the bike frame 29 Derailleur Back Plate.jpeg 3
Rear Derailleur 1 Steel Die Casting, Machining, and Welding The rear derailleur moves the chain to the gears and keeps the chain from becoming loose 29 Rear Derailleur.jpeg 4
Rear Derailleur Nut 1 Steel Threading Holds the derailleur in place 29 Derailleur Cable Nut.jpeg 2
Rear Derailleur Bolt 1 Steel Cold Forged Attaches rear derailleur to bike 29 Rear Derailleur Bolt.jpeg 2
Derailleur Tension Spring 1 Steel Drawing, Coiling Allows the derailleur to take up slack when gears are shifted 29 Derailleur Tension Spring.jpeg 1
Derailleur Pulley Screw (Lg) 1 Steel Turning Attaches derailleur to derailleur pulley 29 Derailleur Pulley Screw Large.jpeg 2
Derailleur Pulley Screw (Sm) 1 Steel Turning The pulley screws attach the derailleur and the derailleur pulley 29 Derailleur Pulley Screw Small.jpeg 2
Derailleur Hanger 1 Steel Compression The hanger allows the derailleur to be attached to the bike frame 29 Derailleur Hanger.jpeg 2
Derailleur Hanger Bolt 1 Steel Turning The hanger bolt attaches the derailleur to the derailleur hanger 29 Derailleur Hanger Bolt.jpeg 2
Derailleur Hanger Washer 1 Steel Compression Distributes the force of the bolt on the hanger 29 Derailleur Hanger Washer.jpeg 1
Derailleur Pulley 1 Aluminum Die Cast and Machined Helps guide the chain when shifting 29 Derailleur Pulley.jpeg 3
Tension Pulley 1 Aluminum Die Cast and Machined Keeps the chain moving while under tension from the derailleur pulley 29 Tension Pulley.jpeg 3
Derailleur Seal 1 Plastic Injection Molding Protects internal components of derailleur 29 Derailleur Seal.jpeg 1































































































































Shifter Assembly

Part Times Used Material Manufacturing Process Function Picture(If Necessary) Complexity
Shifter Mount 2 Steel Die Casting and Machined The mounts allow the shifters to be attached to the handlebars 29 Shifter mount.jpeg 3
Shifter Mount Bolt 2 Steel Turning The mount bolt tightens the mount around the handlebars so it doesn't move 29 Bolt A.jpeg 2
Shifter Mount Bolt (b) 2 Steel Turning These mount bolts allow the shifter to be attached to the shifter mount 29 Bolt B.jpeg 2
Plastic Shifter Cap 2 ABS Plastic Injection Molding The caps cover the inner workings of the shifters to prevent from dirt or debris getting inside, as well as for aesthetics 29 Shifter Cap.jpeg 2
Coarse Threaded Screws 4 Steel Turning These screws hold the shifter cap onto the shifter 29 Threaded Screw.jpeg 2










































Free-Hub Assembly

Part Times Used Material Manufacturing Process Function Picture(If Necessary) Complexity
Ball Bearing 18 Steel Forged and Polished Ball bearings reduce rotational friction and support radial and axial loads 29 Ball Bearing.jpeg 3
Gear Cassette 1 Steel Die Casted then Machined and Assembled Allows the rear wheel to continue moving forward when the rider isn't pedaling 29 Gear Cassette.jpeg 4
Axle 1 Steel Turning Attaches the wheel to the bicycle and provides support for the bearings 29 Axle.jpeg 2
Quick Release 1 Aluminum Die Casted and Extruded Passes through hollow axle and allows for installation and removal of the wheel without tools 29 Quick Release.jpeg 3
Nuts 2 Steel Turning Used to fasten two components together when combined with a bolt 29 Free Hub Nut.jpeg 2
Release Nuts 2 Steel Turning On the opposite side of the quick release, they hold the pressure from the quick release 29 Release Nut.jpeg 2
Free-Hub 1 Aluminum Extruded Allows the rider to stop pedaling while still in motion 29 Free Hub.jpeg 4

























































Seat Assembly

Part Times Used Material Manufacturing Process Function Picture(If Necessary) Complexity
Screw 1 Aluminum Die Cast or Turned Fed through the bracket and used to tighten it to seat post 29 Seat Screw.jpeg 2
Bracket 1 Aluminum Die Cast and Machined Connects the seat post to the underside of the saddle of the seat assembly 29 Seat Bracket.jpeg 2
Washer 1 Steel Stamped Distribute the load of the bolt and nut 29 Derailleur Hanger Washer.jpeg 1
Lever 1 Aluminum Die Cast and Machined Tightens the seat post connection to the frame, loosening allows the seat height to be adjusted 29 Seat Lever.jpeg 2
Spacer 2 Steel Die Cast and Machined Distributes the load of the connection between the screw and nut on the bracket connection 29 Seat Spacer.jpeg 1
Cylindrical Nut 1 Steel Forged Fastens the other side of the screw through the bracket to keep it tight 29 Cylindrical Nut.jpeg 2



















































Miscellaneous Components

Part Times Used Material Manufacturing Process Function Picture(If Necessary) Complexity
Pedal 2 Aluminum Die Cast Allows the ride to transfer energy from their legs to the crank arms 29 Pedal.jpeg 3
Crank Arm 2 Aluminum Die Cast and Machined Transfers the energy applied to the pedal to the crank set 29 Crank Arm.jpeg 2
Bowden Cables 4 Steel Extruded Transfers the user generated mechanical energy to the brakes 29 Bowden.jpeg 2
Chain Rings 2 Aluminum Forged Transfers the user generated mechanical energy to the brakes 29 Chain Ring.jpeg 3
Chain Guard 1 Aluminum Die Cast and Machined Protects the chain from falling off of the chain rings 29 Chain Guard.jpeg 2
Shift Lever 2 Aluminum Die Casting Allows the rider to control the gear in use 29 Shift Lever.jpeg 2
5mm Hex Bolt 8 Steel Cold Forged Fastens components together 29 5mm Hex Bolt.jpeg 2
Metal Bushing 2 Steel Extruded Provides a wear surface for both pulleys 29 Metal Bushing.jpeg 1
Washer (small) 2 Steel Stamped Distributes the load of threaded fasteners 29 Small Washer.jpeg 1
Washer (large) 2 Steel Stamped Distributes the load of threaded fasteners 29 Large Washer.jpeg 1
Springs 2 Aluminum Extruded and Coiled Provides a force that returns levers back to their original positions 29 Springs.jpeg 2
Frame 1 Aluminum Extruded or Rolled Supports the rider and other components and serves for a base for which components are mounted and assembled around 29 Frame.jpeg 4




































































































Product Analysis

Pedal

The pedal is a main component of any bicycle, and deserves a more detailed analysis.

Function:
The pedal is essential to any bicycle. It allows the user to input energy into the bicycle to make it move. They are mounted on an axle that is connected to the crank arms. When a rider pedals, he pushes down on one pedal to start the rotational motion that essentially powers the bike. When one pedal is lowered completely, the other pedal is then forced downward to continue this motion. When the user is riding faster than usual, it is common for them to stand up on the pedals so they have a larger range of motion. When this happens, pedals also serve as a platform for the rider to stand on.

29 Pedal.jpeg


Component Form:
The pedal, for the purpose of simplicity, can be considered to be a rectangular prism. It is symmetrical about the axle when looking from above. It is 3 dimensional as it must provide enough space for a foot to be placed on, and must be high enough to mount about the axle. The rectangular shape is just big enough for you to place a foot on it without having it slip off. It also must be tall enough to fit around the axle it rotates about. The pedal is composed mainly of aluminum, but the axle that is placed inside of it is steel. You can tell this from the general feel of it. The bulk of the weight is clearly in the center, while the outer edges are much lighter. Aluminum was most likely used to decrease weight, while the steel was necessary to keep the internal strength at a premium. The pedals are also essentially hollow, which provides not only an aesthetic look but also allows for easy replacement of reflectors, as well as decreases the weight of the pedal. The black matte finish helps to match with the color scheme of the bike and accents the brown color of the frame.

Processes:
The pedal can either be casted by investment casting, or can be die casted and machined. It is most likely die casted and machined to remove the inside so it can be lighter. Turning must also be used to thread the screw. A notable difference in the two pedals is that the thread on the left pedal is threaded opposite of what we consider normal so that it doesn’t fall off while riding.

Complexity:
When compared to many of the components on our list, the pedals are a lot more complex than the rest. To create the pedals we must use at least 3 different manufacturing processes. The pedal also has intricate details such as dimples for grip and contours and other features that would be difficult to describe without seeing it in person.

Specs:
Length - 4"
Width - 3"
Height - 1.25"
Weight - .25lb

Frame

The bike frame is probably the most important piece of the bike, being that it is the basis on which everything is attached.

Function:
The bike frame is easily the most important component to any bicycle simple because if you did not have the bike frame there would be no bike. The bike frame is where the wheels and all of the components of the bicycle are connected to. The bike frame is the foundation to the bicycle and keeps everything in balance when the rider is on the bicycle. The frame has to be able to withstand the forces it endures during riding, especially on rough surfaces. The bike frame must also absorb the shock that is received when riding. The head tube of the frame has a set of ball bearings that allows the fork to turn smoothly for steering and balance.

29 Frame.jpeg


Component Form:
The bicycle frame is in the form of a diamond frame. The diamond frame is a truss that consists of two triangles, one in the front and one in the rear which is split into two identical triangles. The bike frame is three dimensional. It must be able to be able to hold all of the components and wheels and the rider without deforming in any way. Our bicycle frame is composed fully of aluminum but steel and carbon fiber is often used depending on preference. The weight is distributed evenly throughout the frame so it can stay in balance after all the components are attached to the bike. Aluminum is usually the standard for casual riding and is widely used because it is less expensive. It is also light but very strong and stiff. It can be used for casual riding but can also withstand rock climbing. The look of the frame is a very common look that is similar for most mountain bikes and because the frame is welded together you cannot replace certain parts of the frame you would have to replace the frame entirely. The brown matte finish is completely a preference to rider as to the color that he/she wants.

Processes:
The bars of the bike frame were manufactured by rolling. It was most likely performed under cold rolling to increase the strength of the bike frame and to hold tighter tolerances. The bike frame is then assembled by welding. You can tell that they are welded together just by looking at the frame. It is welded together so that everything stays in place and therefore parts of the frame are not replicable.

Complexity:
The bike frame is pretty complex because everything is attached to the frame so a lot has to be accounted for. This means that there must be multiple locations which can accept a part. These locations not only have to be machined to fit the attached part, but must be in the most efficient area so that the user can easily use the bike.

Specs:
Length: 17”
Width: 3”
Height: 13”
Weight: 12lbs

Crank Arm


Another component that deserves more detailed analysis is the crank arm.

Function:
The crank arm attaches on one end to the pedal and to the front gear system on the other end. There is a crank arm on either side of the bike to allow either foot to pedal. The crank arms allow the rider to gain leverage about the gear system. This allows the user to ride faster, but not have to pedal as quickly. The longer the crank arm, the slower you have to pedal, but this comes at the price of effort. If a crank arm is shorter, you must pedal quicker, but with less force.

29 Crank Arm.jpeg


Component Form:
The crank arm is medium sized. The general shape is a cross, with an extending arm. On the side that attaches to the pedal, there is one hole in the end of the arm in which the pedal will be attached. The arm extends to the gear system where it has one central hole that attaches to the gears, with four other holes that attach and allow the crank arm to gain leverage on the gear system. Without these, there would be too much force on the central hole and could damage the gears. The arm is flat, but has some grooves in it, most likely to increase its strength so it doesn’t bend if the bike falls. It is covered in a matte black finish so as to compliment the brown color of the bike, and follow the color scheme. This is 3 dimensional, as it must be wide enough to be strong, while long enough to provide sufficient leverage, and must extend far enough so that the rider isn’t hitting the bike with their leg while pedaling. Like the pedals, the crank arm is also made out of aluminum to decrease the overall weight of the bike.

Processes:
To make the crank arms, multiple manufacturing processes must be used. First, it is die cast. We know this because we can see some flash is left. The piece is then machined to create threads inside the hole. this is most likely done through drilling and turning.

Complexity:
The crank arm is fairly complex, but not as complex as the pedal. Only two or three processes are used to create the crank arm, specifically casting and two machining processes. As far as it’s shape, is is much simpler than the pedal. The contours in the crank arm are mainly to increase it’s strength and the general shape is not very intricate, but is not a simple shape.

Specs:
Length- 6”
Width- 1.75”
Height- 1”
Weight- 1lb (each)

Solid Modeled Assembly

When designing the solid models for the brake caliper system, there were multiple options but our group ultimately decided on using DDS SolidWorks. There were a number of factors that influenced out decision to use this computer design program including ease of use, accessibility, and overall quality. Most of our group members have some form of computer aided design (CAD) experience which made the learning process much easier and quicker, since SolidWorks does not differ too drastically from the basic AutoCAD software. Also, two group members have access to the software on their own computer, making it possible for the entire group to be working on two different parts at the same time. Lastly, we decided that the compromise between ease of using and learning the product and the overall quality of the parts that were designed in it, made SolidWorks the most logical choice. We decided to create the brake assembly in this program since it required several parts to be assembled and work together. This specific system has also been one of our main focal points throughout the product dissection and analysis, in addition to a few others. However, the braking system seemed the most reasonable to be represented through solid modeling and also provides our group with a greater understanding of how the individual components interact with each other. Here is a list of the individual components, with a video showing how it is assembled.

The CAD files can be downloaded as a *.zip archive here: Media: Group_29-Kona_Shred_Mountain_Bike_CAD.zip

Component List

Part Picture
Bolt Back 29 Bolt Back.jpeg
Wear Surface 29 Wear Surface.jpeg
Cap Screw 29 Cap Screw.jpeg
Seal 29 Seal.jpeg
Pull Lever Washer 29 Pull lever washer.jpeg
Piston Preset Screw 29 Piston Preset screw.jpeg
Support Adjust 29 Support adjust.jpeg
Piston Back 29 Piston back.jpeg
Piston Face 29 Piston Face.jpeg
Cable Plate 29 Cable plate.jpeg
Dust Cap 29 Dust Cap SW.jpeg
Back Stop 29 Back stop.jpeg
Metal Wear 29 Metal wear.jpeg
Caliper Body 29 Caliper Body.jpeg
Bushing 29 Bushing.jpeg
Piston Adjust 29 Piston adjust.jpeg
Bearing 29 Bearing.jpeg
Back Plate 29 Backplate.jpeg
Caliper 29 Caliper.jpeg
Nut 29 nut 1.jpeg
M6 29 M6 1.jpeg
C-Clip 29 C clip 1.jpeg





















































































































































































Assembled View

For a video assembling these parts, click the following link, which will send you to our YouTube video showing the animation of the assembly. [1]

Engineering Analysis

Using engineering analysis, we can determine the maximum force that can be applies to the brake lever that will cause braking, but will not cause the tire to skid. We can also use it to determine the distance needed to come to a complete stop when travelling at a certain speed.

First, we must make assumptions to determine the parameters of our circumstance.

Assume:

-Ratio of Lever to Caliper is 16:1
-660mm wheel
-63.5mm tire
-90%mass on front wheel
-140mm rotors
-Coefficient of Friction of brake pads is .4
-Coefficient of Friction of the tire to the ground is .6
-No inputs other than braking
-Riding on flat ground
-No rolling resistance
-Total mass is 70kg

We then must determine the equations needed to complete the analysis

sum(M)=0=(M1-M2)
F(f)=C(f)*F(N)
KE=.5(m)(V)^2

If we solve the equations with our given assumptions, we can figure out the maximum braking force, and the stopping distance required with our given parameters.

Design Revisions

Here we go into detail about three changes that could be made to the bicycle that we believe increase its overall usability.

Change Frame Material

Due to the complexity of bicycles, it is not easy to change one single component or subsystem, so one of the most logical design changes is to change the material of which the frame is made. An improvement in this aspect of the bike would be to replace the aluminum frame with an even stronger material while still maintaining the relatively low weight of the original frame. Perhaps the most logical material to build a new frame out of would be titanium. When determining whether or not the changes should be implemented, it is necessary to look at both the social and economic design factors. From a safety stand point, relating to the social perception of the product, titanium offers nearly twice the strength of an aluminum frame. This type of frame reduces the chances of injury due to severe structural damage to the frame while riding. A bike with a higher structural integrity will be the more logical choice over a bike that has a frame with a chance of failure during use. Additionally, since the titanium frame is much sturdier and resistant to damage, the upkeep cost would be much lower than that of an aluminum frame as little to no repairs would be needed. From an economic view, since bicycles usually have a product life cycle of anywhere from five to twenty years, this reduced maintenance cost could save the owner money, despite the fact that the initial cost will be more expensive due to the material.

[2]

Replace Brake System

On most bikes, there are three different types of braking systems that can be employed: disc brakes, cantilever brakes, and caliper brakes. As with all similar components there are clearly advantages and disadvantages to each type. Our Kona Shred is currently equipped with disc brakes, however, switching to cantilever brakes is a possible design improvement for a number of reasons. One of the most obvious differences between the two types of braking systems is their prices. Disc brakes are the most expensive choice of the three, while cantilever brakes are the cheapest as they can be installed for just fifteen dollars for each wheel. When deciding which braking system would be more ideal to employ on the bicycle, it is necessary to look at the influencing global factors. Depending on the intended use of the bike based on the areas it is being sold in, different systems would be preferred. For example, disc brakes are the strongest and cool more easily, reducing fade, which would make them the ideal choice in a competitive environment as opposed to commuting use, where the main purpose of the bike is transportation. In this case, the cheaper cantilever brakes would be the more logical choice since it is not necessary to have such a consistent stopping distance.

[3]

Pedal Change

A clipless pedal.
A clipless pedal from Shimano.
Cycling shoes with cleats.
Cycling shoes by Shimano.

The conventional pedals on most bikes are great for around town use, when a rider must constantly dismount. However when efficiency and staying on the bike become more important replacing standard block pedals with ‘clip-less’ models becomes more necessary. Clip-less pedals fasten to a cleat bolted to the bottom of the rider’s shoe, which is normally rigid-soled. This mechanical connection prevents a riders foot from falling off the pedal when riding over rough terrain. It also allows the rider to put all of his/her legs’ rotational energy on to the ground and this connection allows for upward forces. From a global perspective, the downside is simply that one can easily fall over if they forget to disconnect when coming up to a stop. This type of pedal would not be as efficient in residential areas where traffic laws must be obeyed, causing the rider to frequently stop. If the rider is traveling over longer distances on smooth surfaces however, the clip-less pedal is a far more efficient choice. In a fall the pedals automatically disconnect due to the amount of torsional force at the feet. These safety measures help to ensure that even if a rider does fall over, the injuries will not be anymore severe due to the equipment, which is very similar to the way ski bindings are built to eject the rider’s boots in the event of a fall. Taking all of these design considerations into account the clip-less pedal is an excellent upgrade for any rider looking a more confident and efficient ride.










Gate 4

Project Management

Cause for Corrective Action

Previously, our group struggled mostly with work distribution and procrastination. As we progressed through our gates, we got better and better with both splitting up our work, and with completing it on time.

For this Gate, we met the first day of class after we came back from Thanksgiving break. Since this was a Monday, we planned out our schedule for that week. We met on Wednesday and completed the assembly of the bike, with the exception of the parts we were forced to brake or cut. We agreed to complete our parts of the assignment by Saturday night so that we would have all of Sunday to review and revise our write-up.

As far as splitting up our workloads, we were able to assign sections during our Wednesday meeting. We split up the three design revisions to three separate group members. The fourth member would write up everything into Wiki tables, and upload pictures, while the last member would write up the cause for corrective action and a difficulty scale.

Since we received a low grade on our last gate, we needed to do better on this gate writeup. In general, when documenting our procedure, we were sure to be much more detailed and thorough. We took more pictures, and recorded every tool and step followed.

For now, we still have some problems, however minor, with procrastination and work distribution. We will continue to work on these how we have, with working on more regular meetings, and more strict assignments per person.

Product Archaeology

Difficulty Scale

To describe how difficult each step was, we developed another Likert scale ranging from 1-5, with 5 being most difficult. We used a scale very similar to the disassembly process. However, since assembly is generally more difficult than disassembly, we changed some of the criteria. In this scale. Just as in the disassembly process, the difficulty is determined by the highest number that corresponds to either of the criteria. For example, if a step only takes 1 tool and one person, but takes 10 minutes, it will still be rated at a 4.

Difficulty Tools Required Time Required People Required
1 1 or less Less than 4 minutes 1
2 2 4-6 minutes 1
3 2 6-8 minutes 2
4 3 or more 8-15 minutes 2
5 Any specialized tools
ex) Air compressor
More than 15 minutes 3 or more


Subsystem Reassembly Process

To re-assemble our Kona Shred, we reversed our disassembly process. Each part could be put on the same way it was taken off, just in the reverse order, unless it is stated otherwise in our table below. Most parts actually have to be put on in the exact reverse order. For example, we originally screwed the front gear train together in the wrong order, and had to take it apart and assemble it in the right order in order to get the gear cover on properly.

The original assembly may have been different overall. However, for each subsystem, it was most likely put together the same way we did. This is because many parts rely on other parts being assembled first. The example stated above is a good example for this as well. Other things like mounting the handlebar components also provide evidence for this. For example, the shifting mounts must be placed on the handlebars before the brake levers, and these must be mounted prior to the handlebar grips.

Crank Arm Assembly

Initally we mistakenly put the small gear ring on first but determined that this must go on after the large gear ring and the gear ring guard before they are all fastened together. We also used the wrong screws on the large chain ring since their is a small difference in the sizes of the screws for the large and small screws.

Step Tools Actions Difficulty Was the assembly the same
as the disassembly?
Notes (if applicable) Picture
1 Hands Place chain ring guard on outside of right crank arm 1 Yes N/A
2 Hands and 5mm hex key Place larger chain ring on inside of right crank arm and attach the three together using the slightly larger screws 3 Yes The screws needed are relatively short and fat.
29 crank arm 3.jpeg
3 5mm hex key and hands Place the smaller chain ring on the inside of the crank arm and screw in with slighly smaller screws 3 Yes, but the backs to the screws must be accounted for. N/A
29 crank arm 4.jpeg
4 15mm Wrench Place the proper pedals into each crank arm and tighten with wrench 3 Yes Each pedal has the word “KONA” on it, and will be right-side up when it is matched with the proper crank arm. Since the left pedal is counter-threaded, they are NOT interchangeable.
29 crank arm 5.jpeg






























Seat Assembly

Step Tools Actions Difficulty Was the assembly the same
as the disassembly?
Notes (if applicable) Picture
1 Hands Place the small cylindrical nut inside the lever 1 Yes N/A
29 seat assembly 1.jpeg
2 Hands Place the thinner of the two spacers between the lever and the ring 1 Yes N/A
3 Hands Put the thicker of the two spacers on the opposite side 1 Yes N/A
29 seat assembly 2.jpeg
4 5mm hex key Place the bolt through the whole assembly and tighten 1 Yes, but when taken apart, the individual parts listed above all came apart at once. N/A
29 seat assembly 4.jpeg
5 Hands Place the assembly on the seat post and insert into the top of the frame and tighten 2 Yes The seat tightener lever must be placed around the frame itself and then tightened, not the seatpost.
29 seat assembly 5.jpeg















































Brake Lever Assembly

The process described must be done twice, once for each lever for the front and rear brake.

Step Tools Actions Difficulty Was the assembly the same
as the disassembly?
Notes (if applicable) Picture
1 Hands Place the plastic spacers on the inside of the casing and the spring in the hollowed out region of the lever 2 Yes The longer end of the spring should be further from the lever part of the handle.
29 brake lever 1-1.jpeg

29 brake lever 1-2.jpeg
2 Vice grip and hands Place the press pin on one hole of the casing and tighten the vice grip to force the pin through to the ohter hole of the casing 4 No, a different tool was used to remove the pin. N/A
29 brake lever 2.jpeg
3 Hands Thread the brake cable through the casing to the hole in the handle and screw the cable tensioner into the casing 1 Yes For most bikes like ours the rear brake cable goes to the right brake handle, which has the lever pointing to the right.
29 brake lever 3.jpeg




































Brake Caliper

Step Tools Actions Difficulty Was the assembly the same
as the disassembly?
Notes (if applicable) Picture
1 Hands Screw the piston back plate onto the pre-adjust screw until snug 1 Yes N/A
29 bc 1.jpeg

29 bc 1-1.jpeg
2 Hands Put the piston seal into the slot 1 Yes N/A
3 Hands Place the bearings in the ramps on the piston back plate 1 Yes N/A
29 bc 3.jpeg
4 Hands Slide the piston assembly into the caliper housing 2 Yes This should line up with the internal ramps.
29 bc 4.jpeg
5 Hands Clip the plastic wear surface onto the cable pull 1 Yes N/A
6 Hands Pull the washer onto the cable pull 1 Yes N/A
7 Hands Insert the spring into the appropriate holes in the caliper body and cable pull 1 Yes N/A
8 Hands Push and twist the caliper and pull counter clockwise 4 No, when removing caliper no twisting was needed. The step will be completed when the cable pull seats onto the hex on the piston.
9 13mm wrench Fasten the nut on top of the piston 1 Yes The textured side should be facing up.
10 Hands Slide the pre-adjust screw into the piston 1 Yes N/A
11 Hands Place the washer and wear plate on top of the piston back 1 Yes N/A
29 bc 11.jpeg
12 Hands and t15 torx Place dustcap on top of cable pull and fasten with the associated screws 3 Yes N/A
29 bc 12.jpeg
13 Hands Screw the pre-adjust screw into the pad support 2 Yes In this case, the screw is threaded counterclockwise.
29 bc 13.jpeg
14 Hands and needle nose pliers Insert the previous assembly into the back place and secure with the spring washer and C-clip 4 Yes N/A
29 bc 14.jpeg
15 5mm hex key Position the back plate on the caliper and fasten with M6 screws 2 Yes It was difficult to hold both parts at the same time and tighten.
29 bc 15.jpeg






















































































Rear Derailleur

The main problem we faced during this process was putting the silver derailleur plate on properly. If placed on incorrectly, as we did, the mount will not fit properly and must be disassembled again.

Step Tools Actions Difficulty Was the assembly the same
as the disassembly?
Notes (if applicable) Picture
1 Hands Place the smaller spacer on the outside hole and the larger spacer on the inside hole 1 Yes N/A
29 derailleur 1.jpeg
2 Hands Insert the small spring into the hollow part 1 Yes There is a small hole in the bottom of the hollow region. The spring should poke into this hole.
29 derailleur 2.jpeg
3 Hands Place the silver plate on the inside of the derailleur and squeeze the spring in tight 2 No, the spring must be compressed to be inserted. The extension on the silver plate with a threaded hole should be on the side closest to the spring.
4 Hands Place the main bolt through the outside of the hole 1 Yes N/A
5 Hands and needle-nose pliers Squeeze the spring tightly enough to fit the C-clip snugly on the bolt and use the pliers to more securely fit the clip onto the bolt 3 No, the pliers were not needed to remove the C-clip originally. The spring must be compressed a great deal and may require more than one person to hold the assembly together while doing this.
29 derailleur 5.jpeg
6 Hands Place the spacers on their respective pulleys 1 Yes Larger spacer goes on the larger pulley
7 Hands Place the pulleys on the derailleur and the pulleys on the opposite side of the derailleur 1 Yes The smaller pulley goes right on top of the bulk of the derailleur
29 derailleur 7.jpeg
8 3mm hex key Tighten the screws while holding the pulleys and the back plate to the derailleur 3 Yes, but when disassembled the order in which the screws and parts were removed was irrelevant N/A
29 derailleur 8.jpeg
9 Hands Place the cable fastener bolt through the hole below the "Shimano" label 1 Yes, but each step must be done in the proper order when putting them back. N/A
10 Hands On the opposite side, place the spacer and the nut on top of the spacer 1 Yes N/A
11 10mm wrench Tighten the nut with the wrench 1 Yes When tightening with the wrench be sure the nut is securely fastened as it is prone to movement.
12 Hands Put the small spring onto the silver cable tensioner bolt and place the bolt into the black tensioner grip 2 Yes, but the order in which they are placed must be followed for reassembly. N/A
29 derailleur 12.jpeg
13 5mm hex key Place the assembly onto the derailleur and tighten the bolt 3 Yes Make sure the assembly is mounted in the proper direction as shown in the corresponding picture.



































































Mounting to the Frame

Handlebars

We originally placed the shifters onto the handlebars first but then realized the brake handles must be put on first not only due to personal preference but to allow the systems to be operated simultaneously by the rider.

Step Tools Actions Difficulty Was the assembly the same
as the disassembly?
Notes (if applicable) Picture
1 Hands Place the handlebars into the hole at the front of the frame above the front fork 3 Yes They are designed to fit snugly so it should be a little tough to fit in initially.
2 Hands Place the other cover on the other side 1 Yes N/A
3 5mm hex key Screw in the four screws and tighten with the hex key until secure 1 Yes N/A
29 handlebars 3.jpeg

















Brake Handles

Step Tools Actions Difficulty Was the assembly the same
as the disassembly?
Notes (if applicable) Picture
1 Hands Slide the brake handles onto either side of the handlebars 1 Yes The handles should extend towards the outside of the bike
29 brake handles 1.jpeg
2 3mm hex key Place the screws into each hole on the ring of each handle and tighten with hex key 2 Yes, but attention must be paid to the angle at which they are fastened due to rider preference. N/A
29 brake handles 2.jpeg





















Shifters

Step Tools Actions Difficulty Was the assembly the same
as the disassembly?
Notes (if applicable) Picture
1 Hands Slide the shifters onto either side of the handlebars 1 Yes The right hand shifter is the one with more gears.
29 shifters 1.jpeg
2 3mm hex key Place the screws into each hole on the ring of each handle and tighten with hex key 2 Yes, but again the angle at which they are fastened is relevant due to rider preference. N/A
29 shifters 2.jpeg





















Grips

Step Tools Actions Difficulty Was the assembly the same
as the disassembly?
Notes (if applicable) Picture
1 Air compressor (if needed) Slide the grips onto either side of the handlebars. 4 Yes In the intitial removal of the handlebars the grips would only come off with the help of an air compressor to reduce both friction and suction. When reassembling it the grips would go on eventually but was made easier with an air compressor.
29 grips.jpeg















Brakes

Step Tools Actions Difficulty Was the assembly the same
as the disassembly?
Notes (if applicable) Picture
1 Hands Place the brake caliper mounts onto the bike 2 Yes The front mount is slightly longer and is located on the end of the left side of the front fork.
The rear mount is located on the left side at the very back of the bike.
Both are mounted on the inside of the bike with the screws going in from the outside.
29 brakes 1-1.jpeg

29 brakes 1-2.jpeg
2 5mm hex key Place the screws in the mounts and tighten with the hex key 1 Yes N/A
3 Hands Place the brake caliper assembly onto the mount 1 Yes The brake calipers are interchangable, as long as the proper brake wire goes to the respective caliper.
4 5mm hex key Put the screws in the appropriate holes and tighten with hex key 1 Yes The front brake caliper is shown to the right.
29 brakes 4.jpeg
5 Hands Thread the cables through the proper holders to the front and rear caliper assemblies. 2 Yes, but it must be threaded through from front to back this time to make sure it follows the proper path. The front brake handle is located on the left side of the handlebars.
6 Hands and 5mm hex key Place the cable for the front brake into the grove and tighten screw with 5mm hex key and repeat for rear cable 1 Yes N/A
29 brakes 6.jpeg













































Front Derailleur

Step Tools Actions Difficulty Was the assembly the same
as the disassembly?
Notes (if applicable) Picture
1 Hands Place the front derailleur on the frame directly above the pedals 1 Yes The front derailleur is smaller and less complex than the rear derailleur.
2 5mm hex key and hands Close the clamp and put in the screw then tighten with hex key 1 Yes Make sure the derailleur is secured at an angle that keeps it away from the outside of the frame.
29 front derailleur.jpeg















Rear Derailleur

Step Tools Actions Difficulty Was the assembly the same
as the disassembly?
Notes (if applicable) Picture
1 Hands Place the derailleur hanger on the outside of the very back end of the bike on the right side 1 Yes, like most other parts it was returned to its original location. It should sit on the opposite side of the rear brake caliper.
29 rear derailleur 1.jpeg
2 5mm hex key Place the screws in the appropriate holes on the hanger and tighten with hex key 1 Yes N/A
29 rear derailleur 2.jpeg
3 Hands Place the derailleur assembly on the hanger 1 Yes The main bolt should fit inside the hole furthest back.
29 rear derailleur 3.jpeg
4 5mm hex key Tighten the main bolt with the hex key 1 Yes N/A
29 rear derailleur 4.jpeg




































Crank Arms

Step Tools Actions Difficulty Was the assembly the same
as the disassembly?
Notes (if applicable) Picture
1 Hands and 8mm hex key Place the crank arms on either side of the bike and tighten with hex key 1 Yes, but attention must be paid to which arm goes on which side. The pedals should line up again so that the label "Kona" reads left to right on each pedal.
29 crank arms.jpeg













Wheels

This process must be done twice, once for the front wheel and once for the rear wheel.

Step Tools Actions Difficulty Was the assembly the same
as the disassembly?
Notes (if applicable) Picture
1 Hands Place the wheel onto the fork so that the disc brake fits into the caliper and close quick-release handle 1 Yes The wheels are interchangable as long as the caliper lines up properly.
29 wheels.jpeg














Design Revisions

Hydraulic Disc Brakes

A hydraulic disc brake caliper

While there are not many systems that can be replaced in most bikes like the Kona Shred, one of the more popular revisions that are made to these bikes is to replace the mechanical disc brake system with a hydraulic disc system. The main difference between a hydraulic system and a mechanical system such as the one currently on our bike is that a hydraulic system consists of closed systems of hoses and reservoirs that are filled with fluid, normally brake fluid or mineral oil. When compressed by the lever/master cylinder the fluid then forces the pads on the rotor via the caliper and piston. By directly transferring the stopping power generated by the brake lever to the pads rather than by tightening a cable (the cables are prone to stretching), the hydraulic system is able to stop the bike more quickly, more reliably, and with more control.

Hydraulic braking systems appeal more to advanced riders due to the superior stopping power and control that they deliver. Unlike mechanical systems, hydraulic systems have the capability for opposed pistons which can effectively double the possible braking force. From a safety standpoint, it is more difficult for water and debris to get onto the braking surface, which would compromise the stopping ability of the bike. This would appeal to many social factors as riders would obviously prefer a safer system, especially one that has the ability to stop the bike in a much shorter distance. The only downfall to the safety of the hydraulic system that any leaks or cracks in the system could result in the loss of braking power. This can be prevented by regular inspections of the hydraulic system. They also provide a smoother, more linear feel in the brake levers themselves during stopping.

As with most system revisions, an increase in performance and safety will in turn lead to a higher price for the hydraulic brakes as opposed to the mechanical brakes. Most hydraulic systems vary between one and three hundred dollars while mechanical systems such as disc brakes will only cost the rider between sixty and one hundred dollars for standard parts, assuming they will be installed by the rider. While from an economic point of view it may appear that the hydraulic system is far more expensive, hydraulic braking systems can require much less maintenance once they are installed. Since there are very few moving parts within the closed hydraulic system it leaves little chance for system malfunction. While the two systems clearly have their differences, the performance and safety gained from using hydraulic systems over mechanical disc systems far outweighs the increase in price.

Clipless Pedals

A clipless pedal.
A clipless pedal from Shimano.

Of all the systems that operate on the Kona Shred, the drivetrain is perhaps the most crucial to the overall performance of the bike. The main function of the drivetrain is to input the mechanical energy from the rider and transfer it to the wheels of the bike, thus propelling the bike forward. However, due to the nature of a drivetrain and the specific bike we a29re dealing with there is no way to completely remove or improve upon the system as a whole, but there are other smaller changes that can be made to improve its efficiency. One such change is to convert from standard pedals to clip-less pedals.

Cycling shoes with cleats.
Cycling shoes by Shimano.

Clip-less pedals consist of a system in which the rider’s shoes are fastened to the pedal via a cleat that locks them together. The pedals are spring loaded, and have no locking mechanism, so if the rider falls and an excess of force is applied, pedal will disconnect from the shoe. The cycling shoes are made to maximize power transfer and minimize fatigue and pedal weight. Again, as with most improvements, clip-less pedals are more expensive than a normal pedal system for the reason that special shoes must be purchased in order for them to be used effectively. However, the one upside to this method is that the shoes are often durable and the pedals are very strong and resistant to damage or breaking.

When looked at from a social standpoint, the clip-less pedals are seen as a more safe way of riding especially when the bike is being used for jumping, riding on mountainous terrain, and going over rough surfaces. During all of these actions it is fairly easy for a rider’s foot to slip off the pedal and result in a loss of control, but this is clearly avoided by using the clip-less pedal system. Additionally, clip-less pedals increase the efficiency of the rider’s power input to the drivetrain by minimizing unnecessary power loss, which impacts the bike on a global level.





Steel Frame

For many riders, the frame is the most important part of the bike as a whole for many reasons. First, the overall weight of the frame has a great impact on both the performance of the bike and the quality of how smooth the bike is to ride. Additionally, every system must be mounted on and revolves around the frame and as a result, if the frame were to fail then the entire bike would be compromised. In the case of our bike, the Kona Shred, the frame is made of aluminum. However, a key design revision that could be applied to our bike is to change this material from aluminum to steel for numerous reasons.

In an attempt to improve performance on a global level a lighter frame weight is needed. While generally aluminum frames are lighter than steel, a well built steel frame could be lighter if the tube thickness is varied throughout the frame. By having a thinner frame in areas that undergo the least amount of stress and increasing the thickness to the necessary level to avoid failure in the areas of the frame that are under the most stress, the weight of the frame could be drastically reduced. Another consideration to take into account is the comfort of the rider while using the bike. Aluminum frames are often more stiff that steel, which leads to tougher landings when performing jumps and a more uncomfortable ride over rough surfaces. Since steel frames are not as stiff, they absorb some of the energy that travels through the frame through flexing. On the other hand, this flexibility can result in a small amount of power loss while pedaling, but is not significant enough to deter the rider from choosing a steel frame.

At any given weight, aluminum is the least expensive frame that can be made, however these frames have the shortest life expectancy of frame materials, including steel. A typical aluminum frame will be able to be ridden for anywhere between five and ten years before a replacement is necessary. For steel frame, the life expectancy is much longer than this and therefore will be the more economic choice for long term possession of the bike. While the steel frame must be maintained more often and coated with various materials to prevent rust, these costs are very low in comparison to the money saved by not having to replace the frame periodically. Therefore, the more economically intelligent choice of a frame depends on whether or not the owner of the bike plans on using it for a long amount of time.