Originally Posted by 2door
I believe you're going to have to apply more weight/force to the tire than you are doing.
Engine weight alone won't do it. We did some experimentation and came up with somewhere between 30 to 40 lbs to provide enough friction for wet streets. Do you have a way to adjust the roller position relative to the tire?
Also are your tires smooth or knobby?
I can't easily change the position of the roller.
I'm using 29" tires, which are difficult to get cheap. I use the knobby ones that WalMart retails.
This pic is before I moved the gas tank
I believe a partial solution is to use a larger roller (and gear down to compensate).
And another improvement would be to use spring tension to press the roller against the tire. I'm considering a clutch (my clutch consists of lifting and lowering the roller & engine) that's stable in either completely engaged or completely disengaged. I could toggle from one to the other. I really don't use the gradual engagement that is used in a conventional car.
Finally, I must concede a friction drive is simply inferior to a chain or belt.