Bicycle Gearing???

I hear everybody talking about finding the right number of teeth on their fromt sprocket to balence low end torque out with high speed.

Is there any reason that you couldn't get the best of both worlds by using a bicycle style gearing system that lets you switch between to front sprockets? I come from a bicycle repair background so this occured to me immediatly but I'm new to this whole moped thing... Their must be a reason that I've never seen it before.

Is it worth trying? Any thoughts would be great, thanks.


Re: Bicycle Gearing???

Actually, correct me if I'm dead wrong, but in that picture-of-the-week of the puch, it looked to me almost as if it had a derailer...

Re: Bicycle Gearing???

Brandon E /

In the POTW puch has a chain tensioner for the pedal system. It has two chain and sprocket systems, one for the pedals and one for the engine. The engine drive chain is on the other side of the bike.

Re: Bicycle Gearing???

SteelToad /

I would think that with the weight of a moped chain, and the speed that it rotates

at, that anything other than a true path would make it want to come off the

sprocket, or at least cause a lot of wear. On the other hand, with a bicycle being

driven that fast, your legs would want to come off the socket or at least cause

a lot of wear :)

Re: Bicycle Gearing???

Jon DAlton /

I think you could get that to work. You would need to mount the bike gears with the freewheel mechanism because without it, the rear wheel would put tension on the lower part of the chain when you let off the gas, which the derailleur can't take. You would lose engine braking, no big deal. I had a home made scooter that used a bike sprocket, but i modified it to have 2 of the same size sprockets beside each other so it was the width of a motorcycle chain. You would need to put a bike width front sprocket on and use a bike chain. THey would wear out quicker but then you can get old junk bike parts for nothing, i used to have a garage full of them. If you're handy and can machine parts, i don't see why you couldn't do it. the problem seems to me getting the bike gears to fit between the rear hub and the frame, i know on my moped there's not enough room.. It sounds like a good project and you would get more speed out of the bike with 5 or 6 gears on it. I know it would be an improvement to my honda 1-speed.

Re: Bicycle Gearing???

Reeperette /

We tried that once with a puch, but it kept slinging the chain off, especially during attempts to change gears, and it would snap it often as well.

I am sure it's possible, but we didn't have the tools, so we settled for a heavily-rebuilt changer-thingie and just two rear sprockets with the normal front one.

One of the rears we got from a motorcycle junkyard.


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