Group 11 - Beginner Dirt Bike

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Wikipedia Encyclopedia

Group 11 - Gate 1

Group 11 - Gate 2

Gate 3: Coordination Review

Component Summary

Part Numbers were found using the online product owners manual. The are specific to our brand of dirt bike. In parts that are assemblies, part numbers are for the main product of the assembly.

The complexity rating is a rating of 1 to 5. 1 being the easiest to manufacture, while 5 is the most difficult. Our ratings are based on the groups assumptions of the number of steps it takes to assemble each part.

Photos will be uploaded when the website picture uploading capabilities resume. Till then we are sorry for any inconvenience.

Thank You.

Part and Quantity Part Number Function Materials Forces Manufacturing Process Shape Part Complexity Photo
Engine Cover (2) DR70-118 Functional/cosmetic: This part is a combination. It is used to cover and protect the engine from the rider and debris. It also hides the less attractive parts of the engine Metal, probably aluminum because of its light weight No forces exerted Die Casting because of its fine surface finish and the residual risers Rounded edges and hollowness of part lends itself to die casting 1 Engine Cover.jpg
Gas Tank (1) DR70-147 Functional: storage place on dirt bike to hold fuel Main tank is plastic because it is light weight and will not react with the fuel. The hose is rubber to allow it to move The force from the fuel weight would be 5 lbs or less. The forces exerted on the frame would be in equilibrium Plastic blow molding because it is a hollow plastic container. Drilling would then be done for holes. Seams along the edges lend to blow molding. The shape allows for maximum storage in the space allotted. 2 Gas Tank.jpg
Handle Bars (1) DR70-136 Functional: Allows rider to steer the bike. Also gives rider something to hold onto while riding Main frame is metal, probably aluminum because it is light weight. Handles are rubber for a better grip. Only forces exerted would be those exerted by rider. For main ‘U’ tubing is heated then bent into shape. Then horizontal bar is welded into place Shape lends itself to comfort of use. Also shape leans itself to ease of production 3 File:Handle Bars
Engine Block (1) DR70-117 Functional: Takes the fuel provided and turns into in to forward motion, by the use of chemical combustion Metal is used, probably aluminum for its strength and durability. Some parts might require steel for even more strength. The only major forces are those within the engine. These forces would be the result of the fuel combusting and moving within the engine. These forces are equal to the power that drives the bike. This part is an assembly of many different processes. There would be die casting for the main part. Drilling would be done for several connecting holes. Several parts have been welded on as well The shape lends itself to many different processes because it is so complex. No single process could create the engine block as a whole. The side gears and rotating parts would need to be separately made then assembled 5 File:Engine Block
Front Fender (1) DR70-137 Functional: Protects rider from debris. Color of part is cosmetic to give bike an overall color scheme Plastic is used to be light weight. The only forces acting would be if something where to hit this part. The force would then depend on the object and the speed of the bike Injection Molding because of its symmetrical look and risers on underside of part The part is formed to follow the contour of the wheel to proved extra protection for the rider 1 File:Front Fender
Frame Cover (1) DR70-100 Functional/cosmetic: Provide comfortable riding while protecting rider from engine and the engine from debris. Color is cosmetic. Mostly plastic with seat being foam padding with fake leather covering Only forces would be the weight of the rider. This should be 165 lbs or less. Plastic molding, probably injection molding Several parts were formed separately then connected together through screws. 3 Example.jpg
Kick Stand/Foot Pegs (1) DR70-090 Functional: place for rider to place feet when moving and Holds up bike when stationary Metal, probably aluminum because it is light and strong. Forces would be a portion of the rider’s weight. The kick stand would support the bike weight -132 lb Die casting for foot pedals, bending for main bar. Welding and other forms of metal casting for side parts This part is an assembly of other smaller parts. The parts need to be able to move separately causing them to be manufactured separately. 4 File:PHOTO
Electrical Cables (1) DR70-129 Functional: Transfers electricity to spark plug to start engine Wiring is metal, probably copper. Outside is rubber. Connectors are plastic. No forces would be applied. Metal wiring, most likely copper, is cold drawn into desired shape. Rubber housing is wrapped around as an insulator. Plastic ends are plastic injection molded The shape of this part is determined by two specifications. First is what is needed by the bike for the electrical supply. The other is how the different components are assembled together 3 Example.jpg
Rear Shock (1) DR70-116 Functional: absorbs forces caused by movement over uneven terrain Metal spring; probably steel for strength and resistance. This is coated in rubber housing. Forces applied would depend on the weight of the rider and the motion of the bike Metal is twisted in a spiral to create spring. Spring is then coated in rubber to protect it. Ends are milled and drilled to create space to for attachment Shape is defined by the requirements of the shock. A shock designed to absorb 100 lb of force compared to 200 lb of force would be very different, in size and thickness of spring 4 PHOTO
Muffler System (1) DR70-124 Functional: Takes exhaust from engine and releases it at the rear of the bike. Helps to minimize noise from the engine. Whole part is metal, most likely steel. Steel would be used because of its high strength and cheap cost The only forces applied would be the air flowing through the system. On straight parts, this would result in very little force. Where the tubing turns, the forces would depend on the pressure, temperature, and velocity of the exhaust The main system was manufactured by heating steel tubing and then bending it. The outer pans where metal extrusions and then bending. These parts were then welded together. The shape is needed to do the purpose. The turns are needed to slow the velocity of the air. The length of the part is also needed to make sure the exhaust is directed far enough from the engine and the rider. 3 PHOTO
Gear Shift (1) DR70-125 Functional: Allows rider to shift gears while riding bike Mostly metal, probably aluminum because of its light weight The only force would be those applied when the rider shifts gears. Thus the force would only be the a percentage of the rider strength Several parts created, the welded together. This can be seen because of welding marks near joints. The two end pieces are just metal tubing, while the middle is bent metal. The shape is dictated by two things. The first is to allow enough torque to change gears, with little force needed from the rider. Also the shape is designed for comfort of the rider, with there being no sharp edges. 2 PHOTO
Steering Shaft Assembly (1) DR70-197 Functional: Attaches to the handle bars and the front wheel assembly to allow rider to steer. Also holds the front forks, front shock absorbers. Metal, most likely steel composite because it is lighter than other steel part, but strength is needed for this part. Force would be created as the rider turns the handlebars. Depending on terrain there could be resistance to this motion. Also since this secures the shocks, it would get force from that. Parts are created then assembled. The two bases are die-cast, because of left over risers. Several parts are then drilled, and threaded. Parts are then assembled by nuts or screwed together. Shape is needed for several reasons. First is that the parts are rounded, because die casting straight edges is difficult. Also this is a part that the rider could hit, and straight edges could cause injury. 4 PHOTO
Chain (1) DR70-046 Functional: used to connect the engine to the rear wheel, and transfer energy between the two. Metal, most likely steel for its strength and resistance to wear because of friction There would be a friction force between the chain and the gears. There would also be a tension force between the chain links. Individual chain links pinned together with the correct spacing needed for the gears used to create a flexible belt. Shape and size is determined by several factors. One is the spacing between the engine and the wheel. The spacing of the links is determined by the gears that are being used. 4 PHOTO
Rear Frame (1) DR70-107 Functional: connects back tire to the rest of the bike. Metal, most likely aluminum , because of its light weight. There would be two forces applied to it. The first would be horizontal, in keeping the wheel vertical. The other would be a portion of the bike’s and rider’s weight. Square metal tubing is heated and bent into the needed shape. The cross bar is welded onto these parts. Holes and slots are then drilled into the part. Specific Shape is needed because of the forces applied to it. Must be able to distribute weight and not break. 4 PHOTO
Front Shocks (2) DR70-114 Functional: Absorbs vibration from the front wheel to provide a smooth ride for the rider. Metal tubing with a metal piston. The air chamber inside the tubing is pressurized. Forces caused by vibration and sudden changes in height. Shocks absorb forces because of weight from bike and rider. Two cylindrical tubes connect to each other with the smaller one being underneath the larger one. This allows for the smaller tube to fit inside the larger tube where forces are eliminated with the use of an air pocket. Cross sectional area and dimensions of the air chamber depend on the desired force to negate. 4 PHOTO
Front Brake Cable (1) DR70-366 Functional: Connects the hand brake to the wheel Rubber housing covering a metal cable, steel for strength so that it doesn't brake Forces caused by rider when the rider engages the brake Steel cold pressed into wire of desired shape. Rubber covering to prevent friction Shape can change and is formed to connect the hand brake with the wheel brake without the cable affecting other components 2 PHOTO
Frame (1) DR70-100 Functional: Holds components of bike together Metal steel mixture so that it is light but has steel for strength Forces are the weight of the bike and the rider along with the vibrations that were not absorbed by the shocks Metal tubing heated then bent to create shape of bike along with some welding to connect joints Shape is formed to connect all components of the bike while still creating a comfortable riding position 2 PHOTO
Rear Sprocket (1) DR70-381 Functional: Connects chain to the rear wheel Metal/steel for strength Force of engine driving the chain which transfers force to drive the wheel Pressed into correct shape Shape has multiple pegs evenly spaced to fit into the links on the chain 2 PHOTO
Brake Pedal (1) DR70-406 Functional: Transfers force of rider to the rear brake Metal, aluminum for less weight Force of rider when rider engages the rear brake Metal tubes bent and welded. Foot peg is molded Shape has pointed edges to eliminate the rider's foot from slipping off the brake 2 PHOTO
Rear Brake (1) DR70-402 Functional: Presses shoes against brake drum creating friction to stop the bike Metal, steel for strength Frictional forces needed to slow bike Die-casting Circle shape with two "half moon" shaped shoes 4 PHOTO
Number Plate (1) DR70-143 Cosemetic: Provides a smooth surface for a racing number to be placed Plastic Force of air resistance when bike is in motion Molded to create correct shape Square shape with rounded edges 1 PHOTO
Front Axel (1) DR70-159 Functional: Connects the front wheel to the front forks while still allowing the wheel to freely rotate Metal, steel for strength Force that the weight of the rider and bike exert on the front wheel Extruded and then threaded Long cylinder which fits directly in the center of the front wheel 1 PHOTO
Dirt Bike Parts List

Design Revisions

First Revision

Braking system from drum brakes to disk brakes.


Drum brakes are more inefficient than disk brakes because they trap heat within themselves and lose their efficiency as they heat up. This is because the trapped heat causes the pads to expand which makes them not rub against the drum around them using its whole surface area, losing braking power. Disk brakes allow for free flow of air around them and continually cool off as they are used, so they maintain their stopping ability with a minimal if any loss in efficiency. Disk brakes are also easier to replace and maintain.

Second Revision

Cable lines converted to hydraulic line system.


Cable lines rub against their protective coating on the majority of the cable itself. This friction greatly reduces the amount of braking force that could be applied if there was no friction. Hydraulic lines have almost no friction and the fluid used in the lines cannot be compressed, so there is virtually no loss in power.

Third Revision

All bolts in standard sizes.


Disassembly was more complicated than it needs to be because of the time spent searching for tools because half of the dirt bike is assembled in standard and the other half in metric. Also if the company used all the same size or close to the same size bolts in most places the assembly cost would go down because ordering bolts in bulk in abundant sizes would be cheaper and each part on the assembly line could use the same tool to attach their part of the dirt bike.

Solid Modeled Assembly

Our solid modeling assembly was that of the steering column. Please follow the link to a picture of the exploded view. When picture uploading resumes on this website, we will post this picture and more up on our web.

Thank you.


Engineering Analysis

First Revision

Braking system from drum brakes to disk brakes.


-Weight of overall dirt bike is the same for both braking types -Speed, and stopping force applied are the same in both cases initially -Coefficient of friction is the same for all brake pads and shoes

Governing Equations


A= ((Pi)*r^2*w)/2



F=209.5 N with m=70.3kg and Vo=8.94 m/s Vf=0 m/s at 3 seconds


A=2e-4m (cold)

A=2.8e-4m (heated)

Pcold<=Pheated because of expansion From heating

P=748214.2857 N/m


A=2e-4m (cold)

A=2.8e-4m (heated)

Pcold>Pheated because of deformation due to expansion from heating

P=561160.7143 N/m


Drum brakes are more inefficient than disk brakes because they trap heat within themselves and lose their efficiency as they heat up. This is because the trapped heat causes the pads to expand which makes them not rub against the drum around them using its whole surface area, losing braking power. Disk brakes allow for free flow of air around them and continually cool off as they are used, so they maintain their stopping ability with a minimal if any loss in efficiency. Disk brakes are also easier to replace and maintain.