need help with shift kits and drifters

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Kraash

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Jul 29, 2008
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what are shift kits all about... i dont realy understand how the engine gos without the pedels going around in the first place. how do the shift kits work?

and what about single gear bikes with rear drifter breaks? can those be used for the motor mod? do you keep that rear break functioning?:rolleyes:
 
Bikeguy Joe

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
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The shift kit effectively adds a transmission to the china based in-frame engine kit. With a coaster brake, you mount the kit and have one speed just like any other bike. With the shift kit you are using the bikes original drive system as where without it, you are running an ancillary drive system.
 
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Kraash

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Jul 29, 2008
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whats better, why?

will the pedel break system work with a motorbicycle?, or would i have to mod it and add brakes?
 
Pablo

Pablo

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Dec 28, 2007
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Kraash said:
what are shift kits all about... i dont realy understand how the engine gos without the pedels going around in the first place. how do the shift kits work?

and what about single gear bikes with rear drifter breaks? can those be used for the motor mod? do you keep that rear break functioning?:rolleyes:
Click to expand...
Pedals don't turn with engine power, because there is a supplied freewheel and chainring (and spindle and cranks) for the front. The kits work by taking the engine power through the newly shortened kit chain driving a custom made sprocket (all on the left side) connected to a jackshaft, over to the right side and another custom made chain sprocket down via a BMX chain to the chainring/freewheel to drive the normal bike set up.

This set up will not work with coaster brakes, and if the bike is a single speed, there is not much to be gained with a shifter kit.

Shift Kit Info

Bike Requirements
 
Last edited:
Bikeguy Joe

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
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Why "get around them"? They work reliably in all the bikes I've built.

If anything, you would want to augument them with front brakes.
 
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Kraash

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Jul 29, 2008
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i guess i still dont understand shifter kits.. if it drives the same chain that you use to pedel why dont the pedels wip around at 2000rpm when you release the clutch?
 
datz510

datz510

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May 9, 2008
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Same reason you dont have to pedal all the time when riding.. there is a freewheel mechanism in the new pedal assembly that is basically a one way bearing. It allows the chainring to travel faster than the pedals (so you can keep the pedals stationary if you want) while the engine is propelling the bike. If you want, you can pedal. Once your feet get to the same rpm as the chainring, the one way bearing locks in place and allows you to assist the motor.

Pablo or Ghost0, you guys ought to take some video of how the system works.
 
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Kraash

New Member
Jul 29, 2008
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ok ... its starting to come togeather.. once i get my hands on one i think ill be ok =) thanks for the help
 
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longrider.scott

New Member
Nov 8, 2010
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California
I purchased the shift kit from Zoom and started to install the kit. I've had to make many modifications because of the issues associated with the bolts running into each other. The rear engine mount bolts are in the way of the bolts that go through the clutch cover. To remedy this I countersunk the bolts and replaced the bolts with flat heads.
The main issue I have is the front freewheel on the crankset. It doesn't spin true. I wobbles worse than a taco'd wheel. I can't imagine this will be ok for the small chain being driven by the jack shaft. Any ideas about how to fix this problem?
My second issue is with the engine moving in the frame and causing the small sprocket on the jack shaft to misalign with the chainring on the crankset. I tightened the engine clamps to the point where they almost crush the seat tube. I'm thinking I must put a bolt through the front engine mount into the frame to prevent the engine twisting. Any thoughts?
 
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tim turbo

Member
Nov 18, 2009
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fergus falls mn.
Im assuming you did not us the front mount, if the motor is moving that much? You must secure the front mount also! As for the freewheel wobbiing you get what you pay for. I bought a sick bike shift kit and it worked just great!
 
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