Originally Posted by linberl

So the OneMotor system I got may be outside your budget ( or not) but it's awesome. With the small battery and the kind of use we are talking about, I get 20 miles range and it's 130wh. The whole system, all of it, is 4.5 lbs. Everything is wireless and it pops on and off my bike in less than 30 seconds. It also goes on my second bike; I purchased a second mount. So the cost makes sense if you have more than one bike you want to motorize.
However, if it is out of your budget, you might want to look at the PEdrives I posted above. They are basically small friction drives, super light weight, and will give you a boost when you need it but let you ride like normal otherwise. The thing about hub motors is that there's always a tiny bit of drag when you aren't using them and they also weigh more. So for a traditional riding experience, I personally think friction drives are great. Yeah, you might burn through a extra tire each year but they aren't that expensive. I have had my OneMotor for about a year and half now, and I just replaced my tire so just slightly more wear than normal. Now the OneMotor has fancy software and such so it auto adjusts during wet weather - the PEdrives don't so if you live where it is really rainy they may not be a solution for you (or any friction drive that doesn't have the ability to auto adjust the tension).
If that's the case, then your best bet is probably the smallest hub system you can find, there are some Bafangs that are around 6 lbs for the hub motor I believe, and just use the tiniest battery.