Originally Posted by HillRider

Well, among the "old and crabby" are most state's DMV's that consider motorized bicycles, particularly those with gas engines, a motorcycle and subject to the same licensing, registration, driver's license endorsements, etc.

Originally Posted by wphamilton

Not experience, but I've looked into also and have a couple of observations.

Using a small gasoline engine makes practical sense since it's cheaper, and a gas tank carries a lot more energy than a battery. However, the cheap 40-50 cc engines have a reputation of wearing out quickly so I think it's a false economy. The noise and heat are drawbacks. Engineering it is a little tricky because you have to mount it somehow down around your feet, and it seems to me that there's not a lot of room there if you want to retain comfortable pedaling, with pedal assist being pretty much out of the question, and finally I have to wonder if most bike frames are going to handle the vibrations long term.

In short, it appears to be a short term novelty modification. In fact, if you read message boards where people have done this, the guys bragging about the durability have gone 400-600 miles. I don't know about those folks, but 500 miles is a month's worth of riding for a cyclist, so that's not really a good application. So, personally, I've never really been tempted by the idea.

Originally Posted by Slash5

Check your state laws. Here, adding a gasoline engine to a bike makes it a non-compliant vehicle that cannot be used on public roads.

Originally Posted by keg61

it was a VERY short term novelty, the gas engine idea is long since discarded. I'm going to rebuild the drivetrain with MTB components,with a lowest hillclimbing gear of 22 front ring/34 rear cog this winter, with future possibilities of a hub drive in place of the current single front wheel or a mid drive like the bafang running thru the MTB components to the single rear wheel driving wheel. yes, it is not only boat anchor heavy but it drives from only the right rear wheel

Originally Posted by wphamilton

Trike? I like that idea and the front drive would be super easy if it's a normal size wheel. I'd want to add a faring to cut down the power required at higher speeds.

Originally Posted by keg61

high speed has never been an issue, i don't expect it will be in the future. it currently has a 20" front wheel which i was thinking of changing the fork and wheel out for 26" but the consensus seems to be I should stay with 20" because the smaller wheel will provide better torque. I weigh 350 pounds, the trike as is weighs 100+the reason for this project is to be able to get up the hill out of the river valley, where the bike paths are, to home