Chaining to bike's original back sprockets?

[MichaelAngelo]

Hello everyone, thanks for your help in advance.

I was checking out the super-economical Zoom Bicycles 80cc 2-stroke kit. Now, I'm sure what'd make this kit amazing is being able to shift gears to really maximize the power of the engine.

I know these kits have a "clutch lever", it would be awesome if, in some way, you could chain the engine to the bike's original back sprokets. To shift you would just pull the clutch in and shift gears as you normally would on a bicycle, then feather the clutch out so that the gear shifts, then keep motoring along.

Has anyone done this? Is it possible?

Thanks!!!

Michael

 

[motorpsycho]

you can buy a shift kit from sick bike parts that will allow you to do this.
with the shift kit, you don't need to pul in the clutch to shift because it isn't a transmission.
you rely on the bikes derailer to do the shifting, so you can just hold the throttle & bang through the gears like you would if you were peddling the bike.
use the clutch for taking off and stopping only.

 

[MichaelAngelo]

Cool, I just checked it out. It's an extra $150 roughly, wouldn't there be a cheaper way? I wouldn't mind abandoning the ability to pedal the bike normally.

 

[motorpsycho]

the key is having the right size sprockets in the front on the jackshaft (which the shift kit has already) to get the right gear ratio. If you could make a jackshaft with the right size sprockets that would bring the engine chain from the left side over to the right side of the bike, you could do it, and you would have to eliminate the cranks and peddles all together. the shift kit gives you a freewheel front dual sprocket that allows you to keep the cranks and peddles functional.
I have seen single speed back rims /hubs that have the pedal chain on the left, and that would be a whole lot easier than trying to make a jackshaft.
I have seen left side drive, peddle chain single speed hubs used in bmx and freestyle...but i have not seen a multi speed left side drive hub yet.
if you could get one of these left side drive rear hubs, all you would have to do is go from using the 415 chain to a bmx bicycle chain and run that chain from the engine sprocket to the rear hub sprocket.
the thing is tho, i have no idea if anyone makes a left side drive rear hub with multi-speeds.