Motorized Bicycle Assembly Overview

Written by: roboguru

Picture of Motorized Bicycle Assembly Overview

This is a short instructable on how to assemble a motorized bicycle. This was my project when I first started with Tech Shop. 
What's important to remember when you do this project is that not all the bikes will be the same, there are subtle differences that you have to be aware of, and your mileage may vary as far as the degree of difficulty on assembling bikes. Have fun!

Step 1: Step One! Educate Yourself!

Picture of Step One! Educate Yourself!

Before you start this project you have to know what your doing! There are many variables to consider so you have to have a good understanding of what your getting into!

The bike is important! Do not get a cheap bike from Wal-Mart or Target! The construction of the frames are light and could split from the vibrations of the motor. At the very minimum, you should source a bike from a local bike store that is sturdy. A beach cruiser frame is the best option. 

The motor you use is important. Most places on the internet will offer motor kits for your bike. These are universal kits and may not fit your specific application. Be careful before you order as most places have a no return policy. 

The style of bike is important. Going for a vintage look or rat rod look may be your best bet. 

Step 2: Prep the Bike

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Your bike is going to be going a lot faster with the motor on it and the demands are going to be exponentially higher. Make sure you prep the bike for this higher duty. Safety is key here. 

In this example, I added a front caliper brake to assist the coaster brake with braking, and replaced the stock inner tubes with puncture resistant inter tubes. 

Once you add the motor to this bike, the weight will increase drastically and you do not want to have to carry this thing home!

You can also personalize your bike to make it a personal fit. In this case, I powdercoated the bars and seat springs to match the whitewalls. 

Step 3: Get the motor

Picture of Get the motor

Most kits will come similar to what you see in the picture. Just a bunch of random parts, unlabeled bags full of screws, nuts and bolts, and no instructions. To make it even more fun, parts might be missing, stamped improperly, or just fail to show up to the party as far as quality of work. 

Don't panic, think logically. It all has to go together somehow. You might have to retrofit some pieces or custom grind others.  It's all part of the game and will make victory that much sweeter. 

Step 4: Test fit the motor on the bicycle

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Test fit the motor on the bicycle frame. It should fit snugly onto the frame. If it doesn't, then you need to make whatever modifications are necessary to get it to fit snugly. This may require fabricating new brackets for it.

This is the most important step in the process. The motor will have a lot of stressed being placed on it and it absolutely cannot be compromised. These motors have been known to fall off the frame in mid-drive when improperly mounted with catastrophic consequences. Make sure you secure it down.

Step 5: Attach the rear sprocket.

Picture of Attach the rear sprocket.

Most kits will come with a rear sprocket that you attach to the rear wheel. This rear sprocket is connected to the motor and is the primary drive gear for your rear wheel. The most important thing to remember is that this sprocket, when mounted, has to be absolutely dead on in distance from the wheel all the way around. There cannot be any wobble what so ever when the wheel spins  or you run the risk of throwing the chain during operation. 

A near fanatical measurement process is not necessary, but could be helpful!

Step 6: Hook up the drive chain!

Picture of Hook up the drive chain!

The drive chain is what carries the power from the engine to the rear wheel. This is the part of the drive train that is the most fragile but also see's the highest workload. If this fails, it can be catastrophic so you have to make sure that everything is lined up perfectly straight. Variances are not much, and you may  be able to get away with a few millimeters here and there but the chain will run a risk of jumping the teeth is it is any more then that. 

This is also the stage where you will discover if the kit will actually fit your bike or not. Generally, if the chain does not hit the drop outs then you are good, but to be safe it's worth getting a beach cruiser frame or you will have to notch the metal where appropriate. 

A side note; most of the chain tensioners that are supplied with the kits are not very good. There is a high risk of the tensioner getting sucked into the wheel and causing an accident. You might be able to get away without running one, (I did) but other have seen a high degree of success by lathing a skate board wheel and making a custom mount. 

Step 7: Hook everything else up!

Picture of Hook everything else up!

After the drive train is successfully connected, its time to assemble everything else as needed. Carbs need to be connected, fuel lines need to be run, clutch and throttle mechanisms hooked up. These steps are equally important but will just result in the bike being disabled or catching on fire if not properly followed. 

It would probably be a good idea to run weather stripping on the wiring. 

Step 8:

Time to drive it and be the boss on the block! Your not going to get far because everybody will want to talk to you and ask you how to build one. Putting one of these things together is an awesome accomplishment! 

 

 

 

 

Step 9: All of this was done at TechShop San Jose!

http://www.techshop.ws/ws

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