Group 21 2012 Gate 4
For this gate our main objective was to reassemble our product while taking into consideration the connections and functions at a system level. We have included an assembly plan that could be followed by another customer. We have made the conclusion that the important mechanism of the product that allow it to provide the main function of the product is the gear. We will show our design revisions made at the system level. These will include collapsable for storage, gear shifter, master link addition,use of coaster brakes and change of frame material.
Project Management: Critical Project Review
This section includes information about each group member and explains how the group works together as a whole. Problems with the groups and challenges experienced are also discussed.
Table 1: Group 21 Roles, Responsibilities, and Contact Information
|Nicholas Harrison||Mechanisms Expert||His responsibilities include finishing the mechanisms part of the gate as well as making one design revision.||email- email@example.com|
|Jonathan Hughes||Dissection Expert||His responsibilities include reassembling the product, product reassembly write up, as well as making one design revision.||email- firstname.lastname@example.org|
|Garrett Rice||Presenter||His responsibilities will include creating the slide show for the design revision and presenting to the class during on the assigned day.||email- email@example.com|
|Tiffany Vinette||Wiki Expert||Her responsibilities include programming the wiki, allowing for appropriate technical communication. All finished parts of the gates are to be sent to her email before Thursday at 5pm. She is also responsible for the project management portion of the project and completing one design revision.||email- firstname.lastname@example.org|
|Elizabeth Moon||Photographer||Her responsibilities include overseeing the assembly, noting any problems that may have occurred, while taking photographs. She will also be responsible for one design revision.||email- email@example.com|
Cause for Corrective Action
In this section we discuss problems that have been addressed during the project and how we have dealt with them. If there are recurring problems, we will choose different solutions to these challenges. Any new challenges that have occurred after the last gate will be mentioned along with solutions to benefit the group.
We are still having some challenges in the group.
Group members are not attending meetings.
- To address that attendance is mandatory, in the emails, there is a statement saying if a group member does not respond it will be assumed they will be attending the meeting.
- Group members are responsible for responding and letting the other members know they will not be present.
- If this does not occur it will be considered a "no call, no show." In this case, it will be noted and mentioned in the meeting minutes.
- Group members will then deducted points from their group evaluation.
Group members are waiting until last minute to start their share of the assignment and are not meeting expectations of the group.
- For past gates group members are only volunteering for parts that interest them.
- When being allowed to participate, they do not meet the standards of the group for this project.
- For example, they will leave subsections unfinished or leave parts completely undone.
- To solve this problem we decided that one group member would assign parts to the other members, regardless of preference.
- For the next gate the parts will be assigned early enough where each group member putting in an adequate amount of effort should not be a problem. (Assignments for this gate were made late).
- If a group member does not meet the requirements it will be noted and mentioned in the meeting minutes.
- That group member will then be penalized during group evaluations.
Challenges That Have Been Addressed
Having one person be the sole webpage programmer has shown to benefit the group. In the first gate, we were marked down highly for or lack of programming knowledge. Effort was given to learn the language and we have increased our productivity as well as our quality of work of the technical communication required for this project.
The main communication problems were as follows:
- Primary mode of communication was text messaging.
- Miscommunication of assignment due dates.
These were addressed by adding more modes of communication.
- Emails are sent out weekly containing agendas of the meetings, due dates, new meeting times, etc.
- We have set up a photobucket.com account so all pictures will be available for anyone in the group to access.
- We have set up google docs account so all material being worked on will be available to each group member.
- We have meetings about once a week and the minutes can be found in the table below.
These solutions have been working. Each group member knows to look at the wiki page and their emails as reference to which parts they are responsible for and when they are due. Assignments have been turned in on time for the most part.
Our Project Timeline as well as our Meeting Minutes can be found on our Product Management page. They contain what parts of each gate are to be done each week, weekly tasks, individual assignments, and due dates. This page is updated weekly.
Product Archaeology: Product Explanation
In this section of the gate we will discuss the method we used to assemble the product. We have provided a step by step guide that can be used by other customers during their assembly process of the bike. We have also researched a mechanism of the bike and explained how that specific mechanism allows the bike to complete its intended function. Also included are some design revisions at the system level.
To further analyze our product and understand the mechanical workings of it, we carefully reassembled our product. We provided a step by step process describing how our product was reassembled and documented pertinent information such as tools that we used and how we used them. Any challenges we faced throughout the assembly were documented so that even someone unfamiliar with our product could easily reassemble it on their own. We documented how difficult each step was to complete and rated it on a scale from 1 to 5. Because this product is originally completely assembled by hand, each step for assembly is just the reverse process of the disassembly. Overall, due to the nature of the mechanics of this product, assembly and disassembly is fairly easy and can be accomplished with very basic tools and mechanical inclination.
Figure 1: Beginning Product Image
Table 2: Tool List
|Phillips head screwdriver||#2|
|Deep well socket||14 mm|
Table 3: Assembly Guide of Spalding B.L.A.D.E. 10 Speed Bicycle
|Step Number||Process||Description||Tool Used||Difficulty||Picture|
|1||We mounted the tires and rims back onto the frame.||
|2||To make the entire reassembly easier we then installed the kickstand to keep the bike upright on its own.||We placed the kickstand in its respective location and tightened the single bolt with a pair of vice grips (this bolt was not keyed for a screwdriver, socket, or wrench).||Vice grips||1|
|3||We installed the steering stem back onto the frame||sliding it back into the front fork tube tightening the expansion nut bolt with a 6mm allen wrench.||6mm allen wrench||1|
|4||We installed the handlebars back onto the steering stem||placing the bars into the slot on the steering stem and tightening the two 6mm allen bolts on the bar clamp with and 6mm allen wrench.||6mm allen wrench||1|
|5||We reassembled the crank||putting in the innermost bearing, sliding the crank axle in, putting in the outer bearing, tightening the outer bearing cup with a crescent wrench, and then reinstalling the retaining ring and tightening it with a hammer and screwdriver by applying force to the outer notches on the ring.||hammer and screwdriver||1|
|6||We installed the crank arms onto the crank axle||pounding them back onto the crank axle with a hammerand tightening their respective nuts with a 14mm deep well socket and ratchet.||14mm deep well socket and ratchet, hammer||1|
|7||To complete the crank assembly||we reinstalled the pedals onto the crank arms by simply threading them back in to the threaded holes on the crank arms and then tightened them down securely with a 16mm wrench.||16 mm wrench||1|
|8||We then reinstalled the chain||
|9||We reinstalled the rear derailleur||
||15mm wrench, #2 phillips head||2|
|10||We reinstalled the front derailleur||first making sure that it was perfectly parallel to the front sprockets and then tightened the clamp bolt with a 10mm wrench.||10mm wrench||2|
|11||We installed the seat||sliding the seat post back into the frame tubing and tightened the nut and bolt the compresses the frame tubing to hold the seat in place.||13mm socket and ratchet and a 13mm wrench.||1|
|12||We installed the rear brakes||
|13||We installed the front brakes||
|14||The rear brake handle was then mounted to the handlebars||
||6mm allen wrench and 10 mm wrench||1|
|15||The front brake handle was then mounted to the handlebars||
||6mm allen wrench and 10mm wrench||1|
|16||The rear gear selector was mounted to the handlebars||
||#2 phillips head screwdriver||2||See Above|
|17||The front gear selector was mounted to the handlebars||
||#2 phillips head screwdriver and 10mm wrench||2||See Above|
|18||The reflector was reinstalled on the frame||
|19||The water bottle holder was reinstalled onto the frame||tightening the two 6mm allen bolts with an 6mm allen wrench.||6mm allen wrench||1|
Table 4: Difficulty Scale
|1||Very Easy||Time taken to assemble is low (1-2 minutes), physical effort is minimal.|
|2||Easy||Time taken to assemble is low (2-3 minutes), physical effort is minimal.|
|3||Neutral||Time taken to assemble is somewhat low (3-4 minutes), physical effort is moderate.|
|4||Difficult||Time taken to assemble is higher (4-5 minutes), physical effort is moderate.|
|5||Very Difficult||Time taken to assemble is high (5+ minutes), physical effort is high.|
Figure 2: Assembled Product
We encountered very few challenges when reassembling the bicycle. This was mainly because reassembling the bike was almost exactly the same as disassembling it, but in reverse order. Of the few challenges that we did face, they were all overcome rather easily. The first challenge we faced was with the cable. It was very tangled and it needed to be straightened out before we could reattach it. We couldn’t just break the chain since it did not have a master link, so we had to untangle it still attached to the frame, which took some maneuvering. The second challenge was trying to figure out how exactly the derailleur was attached. There was a bolt that fastened the derailleur to the bicycle frame, but no specific hole in the frame for it to attach to. After looking through our pictures of the bicycle before it was disassembled, we realized that the bolt went into the notch that hooked on to the back wheel. Since the way that it was attached was an odd design choice, it had not occurred right away to us that it should be attached that way. The pictures that we took of the bicycle during disassembly definitely made the process of reassembly go very smoothly, and in the end, we were able to fully reassemble the bicycle and get it to work properly.
We have identified a specific mechanism of our product. It is used to generate motion and control system behavior. We will be discussing the purpose of the mechanism as long as how it works and why it is important to the product's functionality.
Technical Name and Purpose
The gearing mechanism is a very complex mechanism that is vital to the drive system in the bicycle. Most bicycles have a different number of gears of different sizes that are quantitatively related to each other by a measure called gear ratio, which is a ratio of the size of relative gears. Smaller gears are generally used for low speed situations, where a lower amount of input by the rider is needed. Larger gears are generally used when a higher speed is desired by the rider, on a flat surface. Some gear ratios are more efficient than others in certain situations. This specific mechanism results in motion of the bicycle. The mechanism name for the gears found on our bicycle is an ordinary gear train. The system transmits motion from one axis to another. In our system, it is connected by a chain and not directly connected to another gear.
How it Works
The gears of a bicycle are connected to a drive chain, which helps in the translation of motion. The chain is connected to the gears of the bicycle by the teeth on the gears, as each space in the chain correspond to a tooth on the gears. Since the gears are connected to the pedals, as the pedals are turned and the gears moved, the chain does as well. This chain is connected to the wheel, which causes the wheels to turn. Since this wheel is on the ground, this results in the horizontal translation of the bicycle through rotation of the wheels. The chain of the gear system is clearly important in the overall process of riding the bicycle. The power output of the bicycle is dependent on the power that is input by the rider, as well as how efficient the gear ratios are for certain situations when riding the bicycle. Simpler bicycles may only have one gear size, where is can not be shifted at all. Many other racing bicycles have dozens of gears, which are commonly referred to as “speeds”.
Equations and Discussion
As far as calculations, a simple calculation is used to calculate the gear ratio of two different gears:
- Gear ratio = (diameter of gear 1) / (diameter of gear 2)
It is easy to see that only the diameters of the two gears in discussion affect the gear ratio. If the user were inputting a set amount of power into the drive system of the bicycle, they would be moving the pedals a set distance, resulting the motion to be translated through the chain to the wheel that would result in the horizontal translational motion of the bicycle. If the rider then input the same set amount of power into the drive system of the bicycle with the only difference is that they selected a different gear of a gear ratio of 2 relative to the first one, they would travel twice the distance as they did the first time.
When analyzing the velocity at which a rider rides the bicycle at during a certain situation, it is important to notice that the distance component of the equation is affected by the gearing mechanism. As explained before, when a rider inputs a set amount of power into the bicycle, the size of the gear is what determines how far the rider will horizontally travel on the bicycle. When the distance in this formula is increased, so it the velocity, as velocity is directly proportional to distance. It can be advantageous of the rider to use a smaller gear size, thus using a smaller gear ratio, when traveling up a hill to travel the most efficient way. When the rider is traveling downhill, it is most efficient to use the largest gear resulting in the highest gear ratio, as a greater distance will be covered.
We have made five different design revisions for the product. Each revision has been made at system level. These changes address at least one or more GSEE factor. Each revision has advantages that benefit the customers in some way.
Collapsable for Storage
For one design revision, eliminate the existing frame and adding a frame that is able to be taken apart easily so the bike can be reconfigurable in nature. This new frame will allow customers to decrease the volume of the bike only by loosening a clasp that holds the frame together. This will then allow the frame to fold over onto itself. Being much smaller and then could easily fit in a trunk of a small car.
Customers who intend to use this product for recreation purposes must sometimes transport the bike either by bike racks attached to their cars or needing a vehicle large enough to fit a whole bike. For social reasons, I believe that making a bike that can collapse to decrease in size will greatly help with transportation issues. Transporting the bike in the trunk of the car is also safer than having it stand up on the top of it, strapping it to a bike rack.
- Customer does not have to purchase additional equipment for transporting the fully assembled product.
- Product will be easier to transport across long distances.
- Customer saves time and energy.
- Safer travelling style.
- The structural integrity of the frame will be at risk.
- It is essentially cut in half and held together by a hinge and clasp.
- Maintenance costs will be higher.
- There is a greater risk of corrosion and damage to the inside contours of the frame.
Master Link Addition
Adding a master link to the bicycle’s chain would improve serviceability by making the chain easier to remove for cleaning and maintenance. The addition of a master link would address an economic factor, since an increase in serviceability, would increase the life of the bicycle and its chain.
Although a very small revision, a master link would be beneficial, while barely affecting the cost of the product since it is relatively cheap to produce. Without the presence of a master link, if the owner of our bicycle wishes to remove the chain from the bicycle frame for cleaning or maintenance, they must break one of the links to do so, which could possibly cause damage to the chain. A master link is simply a link that can be easily removed and then reattached, for cleaning purposes, or in our case, to the remove the chain completely from the frame, which we were not able to do during disassembly.
Change Frame Material
One very practical design revision that could be applied to improve our product would be the use of a chromoly steel frame as compared to the existing hi-tensile steel frame.
Chromoly and hi-tensile steels weigh virtually the same, but chromoly steel is stronger which means that you can use less material and maintain strength. Less material means less weight. Globally, a bike that weighs less draws attention to not only the intermediate rider, but to the competitive rider as well. Having a product that catches the eye of a larger market means more sales. Environmentally, this revision would reduce raw material use because it can serve the same purpose as the hi-tensile steel using less material due to its strength. Because production costs are only slightly higher for the chromoly steel, the overall price of the bike would not greatly increase because less material is being consumed. On top of having an economically friendly product, the overall quality would improve as well.
Use of Coaster Brakes
A revision that could be made to our specific bicycle is the introduction of coaster brakes. Coaster brakes are an idea that already exists, and are an important safety feature on bicycles that have them. This safety factor is a huge societal factor for any potential customer, as many experienced riders feel that this is a safe and reliable way to have a backup system for braking.
Coaster brakes are often a very simple design, that are on bicycles that are designed for riders of many different usage and experience levels. The way to use these are very simple, and they are seen as very reliable but should only be used when necessary if both braking systems are present. They are used simply by moving the pedals backwards, in the opposite direction of when the rider wants to accelerate. The more that the rider wants to break, the more power they should input to pedal backwards to slow down the motion of the bicycle
One obvious advantage for these types of brakes is that the rider does not have to use their hands. This is an extreme and vital advantage for disabled riders, or riders that can not use one of their hands to brake. Also, some riders may think that this is just a more intuitive way to break, which gives them a faster system to use in their reaction time, which can save the rider in certain situations. Another advantage is that chains and cables are not needed, as this will result in a cheaper manufacturing process and it will be easier to troubleshoot for many users. Many riders also feel that this alternative to the regular hand braking system is a much smoother system, as you can brake at smaller increments as opposed to an all-or-nothing kind of alternative. Many riders also like to have one hand free to deliver traffic signals to other riders around them.
As there would clearly be more advantages to having multiple braking systems, this alternative would be rather risky by itself. Skidding is much more possible in this type of braking system, as it is designed to only affect one wheel. That is why this system is often used in conjunction with the hand braking system.
Minor Changes required for the front gear shifter are required for extended use and safety. By bettering the cable system for the first gear shifter we are extending the lifetime of the cable by protecting it from wear and tear from everyday use. The costs of the revision are small if added post-preduction and negligable if implemented during construction. The advantages more than outweigh the disadvantages.
- Extended lifetime of cable
- Increased safety from extra durability
- Slight increase in weight and materials used
- Slight increase in wind resistance