They work well for people who have limited mobility; think in terms of people who would otherwise be able to cycle but would tire easily, for example. They're

They work well for people who have limited mobility; think in terms of people who would otherwise be able to cycle but would tire easily, for example. They're apparently pretty good for cargo bikes where you can pull a heavy load much more easily. I personally don't like 'em because I can get to 15.5mph very quickly and then it's like running into a wall because they're so heavy.