My first report on the practicality of electric bicycles focused on the cost and difficulty of buying and assembling a cheap hybrid electric bike.
http://www.dailykos.com/...
From that experience I gleaned some conclusions. First, electric bicycles really do work and they do represent a valid form of short-distance transportation, as long as weather permits. Second, for commuting it is probably best to get a kit with at least 1000 Watts of power to ensure that the motor will get you up a hill without pedaling. Third, lead-acid batteries are not a good technology for everyday use.
as an alternative to using a car for short
Summary of letter to eBay Guy
A fellow traveler on eBay asked me what I would recommend in an electric bicycle for himself, taking into account his artificial knees. This should answer questions for people with any similar mobility problems.
1. Electric bicycles really work. It’s not a bogus technology.
2. If you plan to use it extensively, get one with a LiFePO4 battery.
3. If you weigh more than 200 pounds, get stronger motor, like 1000W.
4. Convert a used women's mountain bike.
5. For artificial knees this could be a great help.
6. Pedaling is optional, but do it anyway.