Originally Posted by linberl

If you've got a light weight folding bike, it doesn't make sense to me to make it heavy with an electric motor. You should check out the stuff on endless sphere for light home made drive systems. If you're aren't electrically handy (like me) you could consider something like the onemotor.co. I have one coming in a couple weeks for my very light bike friday pakiT. Even with the motor/controller/battery, my bike will still be only 24 lbs. I wouldn't recommend this system for someone who wants to use the motor all the time, or who wants a moped-type, but if you're looking for help on hills, help in headwinds, something you can fly with, and something you can quickly remove when you lock your bike, it is suitable. Even has a custom mount for bromptons!