Friction Drive Kit Questions

Discussion in 'Motorized Bicycle General Discussion' started by Smallwheels, Jun 6, 2010.

  1. Smallwheels

    Smallwheels New Member

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    I'm on my third week of owning a friction drive kit. Overall I like the concept but it's driving me to anger regularly. Not so much about the kit yet, it's the rain. There are only about eleven inches of rainfall in Montana each year and forty-five inches of snow. It seems like those eleven inches are falling into the months of late May and June. That means I'm pedaling with the motor almost all the time just to keep it rolling without the drive roller slipping.

    On the dry days it's great with a few exceptions.

    My drive roller had a diamond pattern on it. With just about one-hundred-fifty miles on it the diamond pattern is no longer as sharp as when new. It now feels smooth with just little bumps. How normal is it for such quick wear on a drive roller?

    Another problem is the rear motor mount bolts that go into the fender mount holes keep breaking. Each time it does that I must take it apart and put it together with new bolts. Now one bolt broke off and the remainder of it is still stuck in the frame.

    My solution has been to create a new mounting point. I've found some thick metal and put holes in it. One big hole goes on the rear axle and the other hole is for the rear support. I drilled it out to hold a bigger 1/4 inch bolt. That should stop the breaking bolts.

    My next problem is that the front mount keeps twisting no matter how tight I clamp it. This causes the drive roller to move away from being perpendicular to the tire. Is that common with friction drive kits?

    The last problem is that my kit required extension bars to move it farther away from the seat. This was needed because my frame has low rear seat stays and the seat down tube is on an angle that is more laid back than conventional bicycles.

    The extension bars need to be kept tight. They hold the front part of the friction kit high enough so that the kit can be lifted off the tire when the rear quick release is loosened. My problem is that the motor side of the kit keeps twisting downward which contributes to the roller pressing more on the left side of the tire instead of the center. I'm wondering if I will need to use super glue to make this stop moving. Has anybody else experienced this and solved the problem?

    On the dry days when nothing is shifting or no bolts are snapping, the kit does a good job moving me down the road at about twenty miles per hour (mph). I have the one inch roller to help me get into the wind and up some hills.

    I've bought a new rear tire that should give the roller a bit more grip. I might put it on this Sunday. Right now I'm using a foam inner tube which means no flats. The new tire is too big for it so I'll need to revert to a pneumatic tube to fill the tire. It will be an extra thick tube with slime AND a tire liner. cvlt1
     
  2. Oysterville

    Oysterville New Member

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    You know, just last week I had one of those bolts vanish on me. The strut (or whatever you want to call it. Engine brace?) flung itself into the rear wheel and stopped it cold. Never did figure out what happened to the bolt. Now I have to wonder if the same thing happened to me that is apparently happening to you. Are we possibly applying too much pressure between the roller and the wheel?
     
  3. Smallwheels

    Smallwheels New Member

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    There is too much pressure on the bolts. It's not that the pressure is unwarranted, it's that the little bolts aren't strong enough for the needed amount of pressure.

    My case is a bit different though. The design of my frame has the fat part of the seat stays going almost all the way to the fender mount holes. That meant that the flat motor support couldn't fit flush against the frame. I had to get longer bolts and put nuts as spacers between the frame and the motor support. Even though I made the nuts tight so that there would be no movement of the bolts, it was just a weaker way to mount the motor support.
     
  4. Smallwheels

    Smallwheels New Member

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    Thanks for telling me about that. I'm going to wire my supports to the frame so they won't go into the wheel if (when) a bolt breaks.
     
  5. Oysterville

    Oysterville New Member

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    I think I'm going to look into JB Welding the danged thing onto the frame, along with the screw. Then throw some baling wire on, wrap that with duct tape, and then slather it in Gorilla Glue.
     
  6. Oysterville

    Oysterville New Member

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    Before I could get to JB Welding, another screw "vanished". Now both screws and brackets are hopefully permanently stuck on. Just too much torque on those screws. Not sure how it can be avoided any other way other than the Loctite or JB Weld route, though. More hardened screws maybe?
     
  7. donutguy

    donutguy New Member

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    I've had my friction drive kit for about 4 months....one thing that might help is to get the fattest tire that fits with little to no tread. I use a Schwalbe Big Apple.

    Another thing that is fairly critical is air pressure-you want to the tire to be pumped up fairly hard and have your knurled wheel pushed down into the tire so the tire deflects 1/8 to 1/4 of an inch.

    Hope that helps
     
  8. Oysterville

    Oysterville New Member

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  9. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

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    QUOTE=Smallwheels;186987]Thanks for telling me about that. I'm going to wire my supports to the frame so they won't go into the wheel if (when) a bolt breaks.[/QUOTE]

    I've never had bolts break on my friction drive kits, even when using common hardware nuts and bolts.

    HOWEVER, if that is a worry, you can drill out the dropout frame holes to accept (Grade-8) 1/4 X 20 bolts. You can also enlarge the long top adjustment slots of the struts to accept the 1/4" bolts.

    While you're at it, you can hacksaw the tops off of the rear support struts. That will allow you to raise the engine over 90 degrees and have easy access to those pesky motor mount bolts.
     
  10. Smallwheels

    Smallwheels New Member

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    What About My Questions?

    I'm enjoying learning from everybody but what about answers to my questions?

    How normal is it for such quick wear on a drive roller?

    My next problem is that the front mount keeps twisting no matter how tight I clamp it. This causes the drive roller to move away from being perpendicular to the tire. Is that common with friction drive kits?

    The last problem is that my kit required extension bars to move it farther away from the seat. This was needed because my frame has low rear seat stays and the seat down tube is on an angle that is more laid back than conventional bicycles.

    The extension bars need to be kept tight. They hold the front part of the friction kit high enough so that the kit can be lifted off the tire when the rear quick release is loosened. My problem is that the motor side of the kit keeps twisting downward which contributes to the roller pressing more on the left side of the tire instead of the center. I'm wondering if I will need to use super glue to make this stop moving. Has anybody else experienced this and solved the problem?

    Thanks.
     
  11. Elmo

    Elmo New Member

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    If the friction roller is made of mild steel it will wear fairly quickly especially in damp conditions when road grit sticks to the tire and you have slippage. Acts like sandpaper. I had the same problem with mine. I had a .7xx diameter roller and just happened to have a piece of 4130 chromo tubing that was a tight fit on my roller. I cut a 2" piece and drilled it and the roller and pinned them together. Took a dremel tool with a cutoff wheel and made lengthwise cuts in the tubing for traction and worked very well. the 4130 wears less than the mild steel. Hope this helps some.
    I don't have a kit, mine is homemade so I cannot comment on your other problems except to say get the smoothest, higest pressure tire you can and run it pumped up hard.
     

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