I've got my first build going recently. It's a small 2-stroke on an old Schwinn Continental. It's not actually on a rack; it pivots on mounts on the chain stays. For that reason, I designed it to use springs for the scrubber wheel "tension". A shifter-like cable setup pulls to disengage the drive.
The maiden voyage was sweet. It bump started quickly and was quieter (to me) than I expected. None of my homemade parts exploded. It gave me a nice boost at low motor rpms.
But my tire had noticable wear after just 10 miles or so. I knew the drive roller (skateboard wheel) was slipping, and it was too large. I took the diameter down from 2" to about 1 1/4" and coated the wheel with grit. It gripped better and ran in a better rpm range, but still slipped and ground the tire down. So I've got stronger springs to try out. I think I'll get it to work well eventually. I don't give up easily.
So does anyone else use springs? If not, if you crank down your friction drive mechanically, is the tire always in contact with the drive roller even when the motor isn't being used? So what I'm looking for is a friction drive that can be engaged/disengaged with the throw of a lever while riding.
The maiden voyage was sweet. It bump started quickly and was quieter (to me) than I expected. None of my homemade parts exploded. It gave me a nice boost at low motor rpms.
But my tire had noticable wear after just 10 miles or so. I knew the drive roller (skateboard wheel) was slipping, and it was too large. I took the diameter down from 2" to about 1 1/4" and coated the wheel with grit. It gripped better and ran in a better rpm range, but still slipped and ground the tire down. So I've got stronger springs to try out. I think I'll get it to work well eventually. I don't give up easily.
So does anyone else use springs? If not, if you crank down your friction drive mechanically, is the tire always in contact with the drive roller even when the motor isn't being used? So what I'm looking for is a friction drive that can be engaged/disengaged with the throw of a lever while riding.