How to Motorize a Pedal Bike
Add a small engine to your pedal bike and you will be glad you did on those long hills on the way home after a tough day. You can salvage a small gasoline engine from an old weed whacker or go green with a small electric engine powered by power tool battery packs. You can even add an engine to a mountain bike. Use the engine for going up the mountain and come down the mountain -- the fun part -- under your own power.
Things You'll Need
- Small engine
- Power tool battery packs (if the engine is electric).
- Bicycle chain gear
- Extended rear wheel hub
- Cabling and controls
- Extra bicycle chain
Instructions
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Install the motor behind the bicycle seat. In this position the chain from the engine to the rear wheel will not interfere with the rider's legs. No matter which type of engine you choose you will need to attach a bicycle gear to the motor shaft. You will be running a bicycle chain around this gear to the hub of the rear wheel of the bicycle. Make sure you have the type of bicycle chain where it is easy to add and delete links. The chain on a motorized bike will be considerably shorter than the length required for a regular bike.
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Get an extended hub so the motor chain can be installed in addition to the pedal chain. You need some sort of clutch on the motor so it can be disengaged when you are using the pedals. The extended hub will have one extra gear, and this extra gear will be what the motor chain goes around.
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Use the extra cabling to run the clutch cable along the frame of the bike and up to the handle bars. This will make it easy to engage and disengage the engine. There should be some emergency cutoff to the engine in case the bike goes down. If you are using a gasoline engine, the spark plug wire is often on top and snaps off. If you do not have such an arrangement, install some sort of emergency cutoff.
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Tips & Warnings
Install a carrier rack over the back wheel -- most bikes already have this -- before you add the engine. It is a good idea to start the engine mounting process by bolting a wooden board on top of the carrier rack and then boring holes in the wood to match the motor mounts.
It is a bad idea to use the motor in the city or anywhere around traffic. A sudden spurt of energy during stop-and-go traffic could prove fatal. Use the engine only when there are no other vehicles nearby.
References
Resources
- Photo Credit Jupiterimages/Brand X Pictures/Getty Images
