Help needed with Friction roller

P

Peter16

New Member
I recently bought your typical 66cc kit for my mountain bike and i am having a ball riding and tinkering with it. While i wait for parts for it to arrive in the mail i figured i would try and keep myself busy.

I acquired a weedwacker and just for fun would like to have a go at mounting it on one of my mini bicycles. Below are 2 photos of what i have to work with. I am figuring out how to mount the drive wheel onto this piece. At the moment i am thinking some kind of grub screw.






thank you
 

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I wont be buying any kits for this. Looking for ideas that can be made from things around the house or a quick trip to the hardware store.

I made a wooden roller with a screw straight through it. Worked for about 2 minutes. i just need a more suitable medium that i can put a countersunk nut and bolt through.

Sorry for the bad pictures, they are stills from an iphone video.




thanks for the replies

Peter auflg
 
Hi Peter, I have been using an 13/16 socket that I rough up with some sand paper and hack sawed some x-shaped grooves into it, so far it doesn't work to bad.
 
Hi peter,

If you want to use the existing weedwacker clutch make sure you pedal up to a fair speed before applying throttle, these clutches use metal-on-metal contact and are not intended to slip while transmitting power. You need a clutch with friction material on the shoes to start from a standstill. The all-metal clutches will either weld themselves together or wear out very quickly while making a deafening screeching noise :)

Also keep in mind that, if you homebrew your roller & mounting bracket, that the roller needs an outboard bearing--just putting a roller on the crankshaft and letting it stick out is asking for trouble. Ideally, the roller has its own 2 bearings, one at each end, with the tire between them, and the engine's crankshaft sees no radial load from the contact pressure of the roller on the tire. You can use a timing belt to drive the roller from the engine's crankshaft, this gives some pre-reduction which allows a much larger roller diameter, giving a larger contact patch between roller and tire--reducing wear and 'chewing' of the tire.

Have fun :)

Ian
 
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