Friction drive wheel material

Discussion in 'Friction Drive' started by a-dam, Feb 19, 2008.

  1. a-dam

    a-dam Member


    I've tried many searches and read many posts, but can't seem to isolate the info on drive wheel materials. A few have mentioned using steel pipe with either welding spatter or abrasives epoxied on for "gription".
    Well, first, here is my situation. Building my first motoredbike; a 1970's Schwinn Continental 27" ten-speed with a 25cc Homelite blower engine. The motor will be mounted on the seat stays just above the rear brake bracket.
    I live out in the country, six miles from the nearest town. Most of my riding is done on well-paved country roads, which is the way I like it, but I would like some assist for the windy days and to extend my range a bit. Most of my rides take me between 10 and 25 miles from home, so I've seen just about everything in that 25-mile radius. I plan to still pedal with the motor going for a speed boost. On leg power I average about 15 mph. I think 25 mph would be great, and I hope to keep the motor around 5000 rpm or lower to keep down the noise and wear & tear. The bike won't be used off-road, and almost always on dry roads. I ride like an old lady going to church on Sunday (unless a farm dog is chasing me).

    Right now, I have a skateboard wheel setup from a seven-dollar KMart skateboard. Urethane, I think. I want to find a material that is hard enough to last a while but soft enough to minimize wear on my bike tire. The skate wheel seems pretty firm; it doesn't "give" when squeezed hard with your thumb. But it seemed to wear a bit during my test run. I had the bike on a work stand in the basement (too cold in the garage!) bump-starting the motor (the only way it will start) and adjusting the carb. I didn't have the tension spring connected during my fiddling - just used hand pressure. I think there was too much slippage, and the drive wheel got a groove in the center from the ridge in the tire. That got me concerned. I'd rather replace friction wheels than tires, but not every two days. It might end up working OK after all if I keep the proper pressure on it. I've never had it out of the basement, so I can't know what it will really do until it gets on the road (come on, springtime!).

    So, finally, here's my questions. What do YOU use for homemade drive wheels? Has anyone had success with rubber wheels? How long do your friction wheels last? What kind of tire wear do you experience? Will a knurled metal or stone wheel be gentle on a tire if slippage is avoided? Got any idea how hard the friction wheel is pressing on the tire? I don't have a fish scale, so I'm not sure about my setup. I guess about 15 lbs total with the motor and tension spring. My skate wheels are 1.5 in wide and 2 in diameter when new. It will have about 1.5 in diameter once its shaped to the tire. That should give me about 20 mph at 4000 rpm. That's what I'm shooting for. I can fabricate what I need once I know what material/surface will work best for me.

    So please share your knowledge with a brotha'. I'll post pics once I get settled in here.

    Talk to me,

  2. gone_fishin

    gone_fishin Guest

  3. kerf

    kerf Guest

    If you have slippage you have wear, tire or roller but somethings gonna "grind down". For that reason I like knurled steel, not over 1 3/8" diameter, 1 1/4" is better. As to tension, there is a trade off, too much cost power, too little cost tires. Roller diameter, tire pressure and profile all have an effect but the needed tension will require a high speed ball bearing on each side of the roller.
    I would look around at some of the friction drive manufactures for ideas as to design. Try Staton, he makes a very good unit but there are others as well.
  4. Esteban

    Esteban Active Member

    I have a vintage Ohlsson & Rice engine on mine, & it has the original steel drive.
    It does very well & does not wear the tire, excessively, as long as you take it easy so it is not spinning/slipping. A tire will last a long time for me & I always have plenty bike tires around here. My motor, being on the front wheel, makes tire changing easier, too. It does better on smoother, wider city type tires than anything else. My owners manual says to mount the motor where the drive wheel compresses the tire about 1/8 of an inch.The roads around here are too rough to mount this motor on skinny bike tires. 1 1/2 " tires work well. Yes, it will slip in the rain. I have seen homemade rigs using pipe. A light mixture of crushed grit from a small grinding wheel, mixed into a paste of J.B. Weld, & coated on the drive roller will give better traction, but may be harder on the tire. I have also seen the drive wheel made from one of those BMX type bike pegs. They are already serrated a little & seem to do pretty well. It seems that we all have to experiment with different things & ideas to best suit our needs.
  5. loquin

    loquin Active Member

    given time, every thing wears down.

    Check out the pics in post #4 here. These are hardened steel rollers!
  6. ibdennyak

    ibdennyak Guest

    On my latest contraption, I used a Tecumseh snow thrower and a caster from a drum dolly. The caster was about 3 1/2 inches in diameter with a 5/8 bore. The engine shaft also had a 5/8 diamter, so I just slipped it on the shaft, and cranked the retainer bolt down hard. Then I started the engine, and ground the caster down to about 2 1/2 inches. It works fairly well, but does like to slip in rain and snow. I use a happy time clutch cable to pull the caster against the tire, and a bungy strap to release it. The engine is rated at 4400 rpm, so it is plenty fast. The caster could be taken down a little more. Wiped out on an ice patch yesterday at maybe 25 to 30 and it wasn't straining. The tire doesn't seem to wear appreciably, and the caster is like $3.00 and half an hour to replace. Unfortunately I blew out the rear tire when I went down, so I had to drag a broken bike about 4 miles home while dripping rain and snow. Ego was bruised more than the old carcass, althogh I wouldn't recommend it as an Olympic event. Hard to convince anybody I did it on purpose. :roll:

    My next scheme is to use a jackshaft scrubber set up with a pneumatic dolly tire. Thinking it might slip less. Smallest I found so far is about 6 inches, so it will have to be geared down. We'll see. :grin:
  7. loquin

    loquin Active Member

    If you used the back end of a gas scooter with a CVT, including the tire & face it backwards? Get an "off road" tire on the scooter rear end & it should get good traction without excessive wear.
  8. fetor56

    fetor56 Guest

    This is what a friend used.It was made in a machine shop,it's ribbed high tensile steel in a concave shape.
    Since it's concave it hugs the wheel more and is better in the wet....tyres also last longer.
  9. I'm using a skateboard wheel assembly, and it seems to work pretty well.
    I do notice some wear, and I think I might get less wear with a steel roller.
    I also feel the skateboard wheel material grinds at the tire a little too much
    even with adjusting pressure, but I'll know more after a few more rides.

    It does work though...
  10. kerf

    kerf Guest

    I always carry a tape measure, if I do a face plant the idea is to jump up and measure the skid marks. I tell anyone watching, I'm doing a government study on bicycle crashes. I have to leave quickly before they start thinking of crash dummy jokes.
  11. ibdennyak

    ibdennyak Guest

    Dang it.....yet another tip a day too late. ;)
  12. kerf

    kerf Guest

    Well, I am an old fool, the trick is keeping it from as many people as possible.
  13. Alaskavan

    Alaskavan Guest

    Denny, it sounds like you'll do fine riding with me next summer. Anyone who'll do 25 - 30 in these conditions is my kinda rider. On topic. Here's my hardened steel roller after about 800 miles of abuse:


    I did change tires a few times, but amazingly, the roller only tore one up.

    And before anyone mentions it, I am aware that it was running a bit off to the side.
  14. uncle_punk13

    uncle_punk13 Guest

    I am using a skateboard wheel on my Island Hopper kit and yeah there's some wear, but it works just fine. There is going to be wear no matter what- it's just the nature of friction drive. Happy cruisin'!
  15. a-dam

    a-dam Member

    Lots of good replies. I'm glad I came to this site.

    I agree with your opinion on the ball bearings. I see a lot of homemade friction drive systems without any support on the end of the shaft. My leaf blower motor has a shaft about 3 inches long and I have an extra "outboard" ball bearing in a pillow block. You can almost see it in the picture. I'll take better pics after the prototyping phase. The drive wheel is a little closer to the outboard bearing than the motor bearings, so it should receive at least half of the radial forces. It's easily replacable and cost eight dollars at "Farm & Fleece".
    There seems to be consensus that slippage will cause more tire wear, and a hard roller should slip less.

    Esteban, how are you?
    Are you the Schwinnbike member that pointed me to this site? If so, thanks!
    It's good to hear that many people with steel rollers are getting acceptable tire life. I've heard about bmx pegs, and if I go with steel, a peg is probably what I will try first (but I don't like their flat profile). BTW, how does that front-wheel-drive work for you? Does it handle OK? No problem with the exhaust noise and fumes in front of you? I can think of a few advantages of having the engine up front.

    Are you THE loquin from dbforums and xtremevbtalk? If we have MBs and programming in common, that would be cool. Hopefully you don't share my many less-desirable attributes.
    Yeah, everything wears down... even us. The best you can hope for is to minimize the problems. You don't want to be replacing rollers or tires too often. Gotta find the best trade-off. The knurled roller in the pics you posted looked kinda small, didn't it? And did he have bushings instead of bearings? If so, its no wonder they burned out. I'd use bushings in a minute if I thought they would last. You could rig up an inverted oil can to constantly drip on the bushing. You would look like a coal miner by the end of each ride.

    People probably make a lot of references about you being from Alaska. So I'll resist the temptation to comment on the Tecumseh snow thrower.
    You've been thinking like me (scary) with the caster wheel and pneumatic dolly tire. I figured that the hard rubber on a caster wheel would be similar to tire rubber, and they would be a good match for each other. And an inflatable drive wheel would seem to be the best choice for wear and traction. Like you said, though, even a small pneumatic tire would be too big for direct drive. If I'm going to go through the trouble of gearing the motor down, I would probably want to skip the friction drive and do chain/sprocket. Of course you can do both. That's another thing I might have to try down the road. I think I feel an MB addiction coming on and see a few MBs in my future.

    Love that avatar! I'll respect your authoritah.
    That roller looks serious. Ribbed for your tire's pleasure? I think the concave profile is important, too; especially on my skinny-tire setup.

    It's good to know that someone else is using a skateboard wheel. We can't know what is best if nobody tries it. I can imagine at least one benefit to a rubber roller. If you get a flat, the roller can't damage the edge of your rim. I suppose the pavement still can, though. Speaking of pavement, ibdennyak has an unfair advantage. He's wiping out on ice, so he's going to get more distance on his face plants. The Olympic medal can be made from a golden sprocket.
    I'll use up the 4 wheels I have first - wouldn't want to waste a whole seven bucks. That is if it ever gets above freezing here.

    Attached Files:

  16. a-dam

    a-dam Member

    I missed a couple people at the end.

    So that is like a before-and-after shot? The fresh roller looks like a smaller diameter. One roller for 800 miles of hard riding sounds pretty good.

    Uncle punk13,
    You're making me feel better about trying the skateboard wheel. Is that Island Hopper a folding bike?

  17. Esteban

    Esteban Active Member

    Yep, the same Esteban. Every type system & set-up will have good & bad points. But, I do like front wheel just fine. Mine is a 1969 motor, by Ohlsson & Rice. VERY dependable. Personally, I don't like the Chinese motors . Too much work to mount, etc., etc., & in MY opinion, their kits are lacking in quality. TYou get what you pay for. The kits from some online sites are of MUCH better quality, albeit, higher in price. Motors by Honda, Mitsubishi, Robin/Subaru, Tecumseh, are hard to beat & made to last !! My motor in the front is not bad. I live in Florida, so the smell of 2 stroke oil, helps keep the " skeeters" off me !!
  18. Esteban

    Esteban Active Member

    Many people think that bike motors are a realtively new idea,,, but look here to see some nice old ones. I know this site has been linked before. An Aussie friend has many of these models.
  19. loquin

    loquin Active Member

    One and the same, a-dam. There are at least a few other programmers & engineers here

    BTW. That drive wheel that I linked to above belongs to srdavo. He didn't say what type it was, but, I recognized it - it's a stanton - mine is just like it (only newer,) and it has bearings at both ends.

    If you're doing a lot of driving in the sand/dirt, the drive wheel WILL wear faster. If you spend most of your time on clean dry pavement, it could take 5000 miles or more before you'd need to pop in a new roller.

    BTW. For the folks who make their own drive wheels out of pipe - you could probably give the surface a coat of the (epoxy?) paint with grit in it that's used for traction on steps. If it IS epoxy, it would be a fairly durable coating that should last for a while. Then, every month or so, depending on the wear, slap on another coat ...

    It might help extend the life of a knurled steel roller that's starting to wear down.
  20. Alaskavan

    Alaskavan Guest

    The new roller in the picture is smaller. Once the trike is finished, it will be my road bike. The Trek and the Mitsu will be used either in town, or off in the hinterlands. I think the smaller diameter will work better for "stop and go" and the very rough roads out in the wild.
    Loquin is probly right about sand/dirt. In the summer here, there is a LOT of rock dust from the glaciers, and in the winter/spring/fall there is sand spread on the roads. It probably contributes to the wear on the roller.