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Old 01-06-2012, 02:09 PM
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maurtis maurtis is offline
Motorized Bicycle Elite Member
Join Date: Dec 2011
Location: Kyle, TX
Posts: 707
Default Re: Mongoose XR-75 MTB Weed Eater Friction Drive

I went with a scissor lift, just in case I needed to lift the motor off the wheel if the stock clutch did not work like I had hoped. Which is what happened, lol.

There is a little more angle on the motor than I would like, but that is basically the aluminum flexing. I need to add some more support...

For bearing support on the non-motor side, I just have a 1/4" bolt going from my bracket into the bearing hole. It does not add as much stability as I had hoped, though, and if I were to do it again I would build a fully enclosed FD system like others have done. Pretty much a support system that covers the top of the wheel and has a bearing on both sides of the roller. This system seems to work ok, though, so at least I am happy I gave it a shot!

The springs I used to add tension were not very strong, so I looped them under the swingarm for some extra pull, lol. They will get replaced with shorter springs and possible turnbuckles for tuning.

For the throttle and scissor clutch, I used bike brake levers mounted backwards. I was pleased with the quality of the levers since they were only $12 for the pair at a local bike shop.

And I knew the old, dry-rotted mountain bike tires were going to be an issue with slippage, especially with using a socket as a drive roller, so after the shakedown run, I replaced the rear with a Bell Streamliner balloon tire that I picked up from Walmart a few days ago. Apparently these wear quickly in FD applications, but we shall see how long it holds up.

My initial run was just up and down the street (with my motorcycle helmet and gloves on). It ran much better than expected! After double-nutting and locktite-ing the nuts the shook loose, I went for a longer ride, about a mile, around the neighborhood. With that small drive roller and small contact patch, I was still moving at a good clip, maybe 15-ish on the flats (I am 205 lbs). She even carried me up the hills. I cannot wait for the next ride, with the new back tire on I should get some more bite.

Now I am looking for something to put around the socket for a little more diameter and traction. I think a piece of rubber hose with a 1" ID epoxied to it, maybe? Small RC car tires?

Anyways, if you read this far, thanks!!!

Last edited by maurtis; 01-06-2012 at 02:21 PM.
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