I have had a Tern JoeC21 (entry level folding bike, with 7 x 3 gears), and it had a Bionx ebike kit installed over 3 years ago. After nearly 3,000 miles, mostly going to work, the folding function made it possible to keep the bike in my office. It also made it easier to fold up in a crowded train. It also made it easier to fold and stow while visiting friends. It also can fold up and fit in a medium size car trunk. When I got this bike it was $400 for the bike, and the kit was around $1,600.


The ebike motor is strong enough (350 watts) to get up some very long steep hills where I live, and it also makes a very long commute feel very easy. So the bike is used many times when I would have used a car before (for short errands). I believe it saved me a lot of money (train fares, gas, parking in a major city with very terrible parking). In fact, many times when I thought that driving would save time, parking was so bad and time consuming that the bike would have been almost as fast and much cheaper and cleaner. One caveat: parking a bike in a big city means you need to invest in a great lock and use it as designed to lower the risk of theft. Another caveat: battery life fades slowly over time, so range reduces over years.


Generally, I've been happy with the Tern folding mechanism because it is easy to deal with and fast to unfold and fold; however, it has a little creakiness after a lot of stress. I prefer the much stronger folding mechanism is on the Montague bike that I got for fun rides; none of the structural tubes are cut at all due to the folding design.


If you have more specific questions, just reply.