Re: Insane 7 speed friction roller drive with common engines (tanaka, pocketbike, etc
Sure. It was in the mid nineties and , Although there were pictures taken, the film is / was never developed or lost. Yeah, slipage and chain wear were the ones. knurl would be the winner on your mt bike hub for sure!. The time wait for compounds to set vs their useful life including disassemble and reassembly really sucked. I was using various reinforced rubber hoses pressed onto the hubs. Hit your local oilfilter service house and look at their 2-inch+ diameter hoses in various strengths. (depending on your hub size)
THe other 'gotcha' is having the hub-flange of the roller cutting slowly into the tire. I would grind off one flange down to the hub, set in some glue, and press like a mofo until I set it all the way to the other flange. THen I offset the roller so as to keep the one remaining flange away from the tire. I used 3 speed sturmey archer hubs for the rollers and a 3.5HP 4 stroke for power(rear rack mounted). I removed peddles and front sprocket, then welded both cranks forward permanently . I addded a foot lever to pull the rear coaster break. Acceleration was good and fun from zero to second gear top out. Shifting to third and applying full power put too much slipage and heat on the rubber, reducing its life hours dramatically. After countless reapplications of rubber in various strengths and with various glues, I resigned myself to metal roller on dry days. Wet days with sand was good for a spin... but alas... WET! . I say go ahead and do it if max efficiency is not the end goal. It is worth it for the thrill of the shift alone!
I still advocate the cheap china motor with the 5 to one reducer using a 12 tooth sprocket. COuple that with a torker tricycle 3-speed tranny(by shimano) which has a sprocket on the output body, and you can use an off-the-shelf 32-tooth sprocket on your rear wheel and get the same results as I do on my motorized recumbent.
Attached is all the off the shelf parts together. motor, reducer, torker tranny, to rear wheel .
THe math is. motor 1/5 tranny ( 12 tooth) shimano(21 tooth input 22 tooth output 75% 100% 133%) 9.5 inch rear wheel with 16 tooth freewheel sprocket. This arrangement requires no peddling(the vehicle has none) even when starting on a hill from a dead stop. Hits 40 without a problem, and using a drop resistent HD bmx chain you never have to adjust anything. All I have to do is make sure the reducer has oil and the chain is lubed. I highly recommend KMC510 bmx chain. Virtually no wear past an initial break in.
If you can get the roller going more rapid than chain, by all means do it.
