friction drive help

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deacon

deacon

minor bike philosopher
Jan 15, 2008
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Let me say first of all, I don't really like everything about any of the kits I have seen. But I do want a kit or at least simple directions on how to do it. I am presently using a friction drive that I think is superior to anything out there in a kit. It is powered with an electric motor so I'm not thrilled with that part.

The drive wheel of the system is the complete rear wheel of an electric scooter. It comes complete with a #25 sprocket. So the easiest thing to do is tor build a rectangular frame around the wheel and bolt the axle to the frame. I can then mount the frame to the bicycle just like the kits on ebay and around. I use a heavy strap steel strap henge on the steel wheel frame and the other end to the mounting plate bolted to the bike. It makes a nice mouth that can be adjusted to the angle of the frame without any problems. That is all cool.

The help I need is finding a way to mount a #25 sprocket to the bell of a centrifugal clutch and the right engine to put it on. Any ideas would be appreciated.
 
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Albula vulpes

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Mar 16, 2010
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deacon said:
The help I need is finding a way to mount a #25 sprocket to the bell of a centrifugal clutch and the right engine to put it on. Any ideas would be appreciated.
Click to expand...

Not sure if I fully understand your project. Is the scooter rear wheel going to drive the 26" bicycle tire? Anyway here is an engine that has the 76mm clutch bell with a sprocket already on it. I pretty sure it is a #25, but would check with the seller first.

47cc 49cc 2-Stroke Engine Pocket Bike Mini Quad Bicycle - eBay (item 220666695950 end time Dec-07-10 16:15:35 PST)


Here is just the clutch bell drum with sprocket for different engine choices......


6 T Gear Box Clutch Drum 47cc 49cc Pocket Bike ATV Quad - eBay (item 180513424325 end time Dec-23-10 17:41:32 PST)
 
deacon

deacon

minor bike philosopher
Jan 15, 2008
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I use this drive now with an electric motor. The scooter wheel sits on top of the bikes rear wheel. When the scooter wheel turns it turns the bike wheel. It is rubber on rubber so the tread of the bike tire is immaterial as is the weather conditions more or less.
 
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Albula vulpes

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Mar 16, 2010
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Most of the rollers that drive the friction units are from 7/8 inch round thru 1.5 inches round. Running a rear scooter tire as a roller I would think would make your gear ratio very high. Not sure how it would work. Interested though.


My roller is 1.25 inches. Divide that by 26inch tire and get the gear ratio.


Lets say if you get a 6 tooth #25 driver sprocket to turn the 80tooth scooter rear wheel sprocket then....................................................

6 divided by 80 = ?......................................

Then lets say if your scooter rear wheel is 8 inches in diameter and is going to be turning a 26 inch wheel......................


Then..............

8 divided by 26 =?.......................................

Multiply the numbers together and if you get something in the range of a gear ratio that is 18:1 thru 22:1, go for it.


I think this sounds right. If someone else wants to chime in that knows, shoot.


What gear ratio do you get when you plug your numbers in?

Hope this helps,
 
deacon

deacon

minor bike philosopher
Jan 15, 2008
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I don't care for the metal roller wheels. The tire gets a lot less wear with the rubber wheel that's why I would like to use the rear wheel assembly, if I can. I built a lot of friction drive with the metal rollers and always found them wanting. If you ever have one run wild while you are holding the bike in place it will wear a flat spot on the tire or it did for me at least.

I run a motor that turns about 5000 rpms with a sprocket about an inch in diameter that then turns a sprocket on the wheel that is about 6 inches in diameter that is hooked to a wheel with a tire about eight inches in diameter that turns a bicycle wheel. Unless i am mistaken the bicycle wheel size only matters to the pedal gearing. Since when the wheel on top of the bike wheel turns an inch, it turns the bike wheel an inch. So its all about how fast the wheel on top turns. At least that is my understanding. Same with roller size.

I think with a 7000 rpm motor the wheel on top would do just fine up to about thirty mph is my gut feeling. It will do close to twenty mph with the 5000 rpm motor. I have looked at the pocket bike motors and they might work except that they are kind long to turn sideways on the frame on top of the rear bike wheel. I know t his makes no sense unless you have done it, or can see the rube goldberg drive. I would have to line the chain drive up so it would be a bit difficult to mount I think. I will probably wind up buying a kit anyway. Maybe I will end up modifying the kit to use a sprocket instead of a roller who knows.

Then again I am waiting until spring to actually do anything.... or that is the plan. In the meantime I'm gathering ideas so keep them coming.
 
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Albula vulpes

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Mar 16, 2010
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The metal rollers do take their toll on the rear rubber tire. I think you have to be a manager or be very conservative with the throttle to eliminate excess tire wear.

The engine I run right now is too powerful for friction drive. I can be rolling about 20mph down the road, floor it and still spin the roller on the rear wheel making slippage.


It is fun as all get out though riding this thing. I think these friction drives are better suited for the lower HP 4 strokes like the Honda GX35 or Subaru eh035.


If your going use sprocket to 26" rear wheel, I would avoid a rag joint, or double nut the S.O.B. They suck bad..............................., and render your bike useless after spoke breakage.
 
deacon

deacon

minor bike philosopher
Jan 15, 2008
8,114
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north carolina
I have had my fill of sprocket on the bike wheels. Never had a bit of luck with them. I like friction drive and i like the scooter wheel as a drive wheel on top of the bike wheel. If all else fails, I might take my cutter to the kit roller holder and cement the thread from a tire to the roller in there. I really want to use the scooter wheel though I have had really great luck with that on my ebike.

Like I said I will be giving it a lot of thought until spring.

And I agree if you are going to run friction you need torque not rpms I think. Personally 25 mph on the flat is plenty for me. I have medical balance issues.
 
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Albula vulpes

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Mar 16, 2010
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I like innovation. I think you would be hard pressed though to take a tire tread and mount/glue it to the metal roller though. The circumference is very small and turning 6,000 rpm, I do not think It would stick for very long. I could be wrong though.

If you got the scooter wheel, and took the tire off of it and then mounted/glued a bicycle inner-tube to the inside channel of the wheel, then ran just the inside wheel channel of the scooter wheel on top of a 26" bicycle tire, I would think it would work. I would try and get it in a gear ratio of 18:1 to-thru-22:1 though.

I would think it would be/serve like a baseball pitch machine. The baseball pitch machine has two rollers and when the baseball catches them, It shoots. You would be just shooting a 26" tire instead of a ball.

Providing a channel like the inside of the scooter wheel, would give it extra grip as well. It could not only grab the top tread of the 26" tire, but could also grab the sidewalls of the 26" bicycle tire.

Would like to see how it turns out. Wish you success,
 
corgi1

corgi1

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Aug 13, 2009
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The scooter wheel (still factory hooked to the motor in the frame work )will move the bike at (almost) the same speed as the scooter went on it's own ,when run as a friction drive,,,,,,A smaller roller will move the bike slower ,but will climb steep hills and go down the road ,just at the low speed ,,,,,The scooter comlpete set up motor/wheel ,used a as a friction drive is moving the road surface of the bike tire the speed the scooter would go on its own
 
deacon

deacon

minor bike philosopher
Jan 15, 2008
8,114
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north carolina
absolutely true except that if you use the higher bike gears to pedal now and then you can get better pickup and even high top end speeds on small hills. So the scooter bike combo is actually a little faster overall. At least that is my experience with it. the only thing I am thinking is that the gas engine would have a few more rpms and a lot more range.
 
corgi1

corgi1

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I'm thinking again(that thinking could be dangerous,lol),,,,what if there was a set of pullies like the varible speeds on an old drill-press(little to big and big to little) for changing speeds and pulling power,just move the belt from pully to pully for different needs
 
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Albula vulpes

New Member
Mar 16, 2010
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Saw the new BMP combo drive. Wouldn't want one. It complexes what is/was simple. (friciton drive) The last thing I would want on my rear wheel is a ragjoint. I actually picked up another friction drive. I have 2 now.
 
deacon

deacon

minor bike philosopher
Jan 15, 2008
8,114
9
0
north carolina
I have a spare rhino drive (scooter wheel with scooter motor. I think I am going to convert it to a gasoline motor driven wheel when I find the right motor combo for it. I just don't have much faith in the pocket bike motors on ebay. Has anyone built with one of them?
 
B

Build-a-beast workshop

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Dec 18, 2009
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i built a bike with a china scooter motor.the scooter came offhand, so when i went to find parts, i couldn't find any manufacturer's name or number of CCs.i've seen similar scooters with the same engines, they all have a built-in oiled gear reduction box, right hand drive. some have electric start and some dont.most have red plastic shrouds with a black plastic intake and large rectangular muffler, ive seen them on pocketbikes and the super tiny go-karts to. i can vouch that they are good engines, i've had a couple, and still do.as to who makes them......its a mystery to me. the bike itself had a three-speed hub and no pedals, since the motor was right hand drive. it liked to eat through sets of pawls, and i always found myself rebuilding the 3 speed hubs or throwing in other wheels with the hub.it was a fun machine though, still have its engine.
 
B

Build-a-beast workshop

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Dec 18, 2009
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went and looked on ebay, saw the red and black one with the carb on the side, right hand drive, 49 cc that was like mine.then i saw the pocketbike black ones with the carb on the bottom and some had a dry gear reduction box,on the left.....having a carb on the bottom would probably keep oil/gas moving through everything nice and smooth. i noticed on little snowblowers that a 2-stroke will eat up it's bearings quicker with a carb on the side, vs. on the bottom.
 
deacon

deacon

minor bike philosopher
Jan 15, 2008
8,114
9
0
north carolina
Thanks for the info. If I put it on a friction drive there should be very little strain and I won't really need the gear reduction. At least I never have on a friction drive E bike. I want it to turn the six inch ebike wheel as it rides on top of the bike wheel.
 
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