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i am making a friction drive motorbike Answered

i am make a direct friction drive motorbike with a bmx bike and a 25cc weedeater i am going to mount it on a hinge and i will use a spring to tighten down the spindle. the hinge is just some angle aluminium mounted to the two bottom holes of the engine. the aluminum is just connected two a bolt that goes over the brake cross section. the spring goes from the end of the angle aluminum to the wheel axle. is that enough or do i need more?



Best Answer 8 years ago

I'm not sure if connecting it to "a" bolt that goes over the brake cross section is going to be strong enough. You need two attachments so it won't twist or wiggle.  Expecting the spring to keep it straight is not enough.  The springs only duty is to hold the motor against the wheel.  Grab the motor and shake it side to side.  Does it wiggle in the mounting?  If yes then it's not secure enough.

Do you have a way to remove power in an emergency?  Other than just killing the motor.  A better system than a spring would be a cable running to an extra brake handle so that you squeezed the handle and the motor goes against the wheel.  then if you get in trouble you let go of the handle and no more power.

no it's not, it's just missing the gun part and that's it.

but it doesn't weld at the moment you couldn't turn it on right now and start welding so it is broken

friction drive is ok , mounted in permanant contact with th' rear wheel works besr ( you MUST have a centrifugal clutch) you will need to experiment to find th' right size driving wheel to suit th' application ! i have built several and sold all i could make , FAST !

but i have saw alot of people who did this without clutches plus i dont have a clutch for the engine, why do i need one?

Because when the tire stops, so does the motor if you don't have a clutch to let the motor idle or some other way of disconnecting the two.

well i made it and it goes about 20mph but thanks anyway i just didn't know what you meant by "( you MUST have a centrifugal clutch)" i thought you meant it would bust the engine or something

Do it with a chain and sprocket, get someone to weld you a sprocket on the crankshaft if you have to.


Yes I know, I'm offering an alternative either for you or anyone else who might read it.
Anyway, please photograph it and publish it, I'd like to see what you build.


dude i live across the street from you and i have a welder!!!!