Classical friction drive works with a roller on the tire either driven directly from the engines crankshaft(most common) to some form of primary drive to the roller, In all cases a roller is involved. The crankshaft drive roller is as simple a drive that exists for a bike(excluding maybe jets or rockets). When you mention gearing, if you are referring to using the bikes gearset, the thats another whole drive system. Most FDs operate in the low to mid 20mph range, though it has been shown by members here that with the right engine/roller combo can reach 40+. I have chain and belt drive bikes for that speed range. I pefer to ease along on my FDs in the mid 20s. In any case I like em!
