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i am making a friction drive motorbike

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?

15 answers
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Jun 26, 2010. 7:08 AMRe-design says:
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.
Jul 8, 2010. 7:04 AMdonovanl12 says:
no it's not, it's just missing the gun part and that's it.
Mar 5, 2011. 6:10 AMdonovanl12 says:
nope, not broken.
Jun 27, 2010. 2:02 AMgearhead1951 says:
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 !
Jun 27, 2010. 6:46 AMjtobako says:
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.
Jun 26, 2010. 11:30 AMlemonie says:

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

L
Jun 27, 2010. 12:25 AMlemonie says:

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.

L
Jun 27, 2010. 7:04 AMdonovanl12 says:
dude i live across the street from you and i have a welder!!!!

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