Thanks guys.

I joined a motorized bike forum, as suggested, and learned that these guys seem to spend a LOT of time on maintenance, which is not what I had in mind.

I like tinkering with things myself, but not if I'm going to use it as a serious commuter vehicle. And besides, I wondered about the gas-smelling clothes. I wear nice clothes to work and don't want them to smell.

That said, I have quite a quest ahead of me for the right electric kit. I found a 395 dollar one that is made by Wilderness Energy (a brushed motor, 36 volt) with SLA batteries from a company in Boise, Idaho (found it on Ebay, of course). If it's reliable and gets me the four miles to work, that would be great. I have three rather large hills that are about three hundred yards each. I can peddle up them in second gear or third without stopping, but by the time I arrive to work I'm hot and sweaty. That's great for a morning workout, but not for work. I can't shower at work and I have to be ready to teach the kids when the bell rings.

I do not plan to modify my Trek 7100 at all. I love that bike. I can ride it everywhere. It's light, shifts fairly well, and the gears get me up all the hills around here. It's a great workout. But I don't want a workout on the way to work.

Think a 36 volt brushed motor on a beach cruiser can get me 4 miles with a moderate amount of hill climbing?