Bike Frame Suggestion
You might see if you can find a Raleigh Gruv 2. They are out of production, semi crank forward (CF) frames that are going for $250, but were retailed at $400 or so in my neck of the woods (SE MN). The frame is perfect for install, and it has 26" mountain tires, 36 spokes etc.
I bought one and the GEBE kit goes on it with ease. I like things simple, for the most part, and not into fabricating frames etc. as I mostly pedal.
Pics of frame are located on this site.
Of course, there are scads of used Treks out there and other good mountain bikes. You can also check out local police auctions and neighborhood people who put repaired bikes out on their lawns every week-end in the warm weather.
Frankly, I would stay away from the cheaper production bikes. Speeding along at 15 to 30 MPH may not be fast, but a failure can hurt.
Use the search attribute on this site for good tricks, tires and short cuts from those who learned the hard way and were nice enough to pass on the information.
Two things I would suggest to save later grief:
Have GEBE supply you with a rim with heavy spokes and 9 inch rear axle. It is not that expensive and can be used as a switch wheel if necessary. The longer axle will offer much convenience later, with double nut locking the rack in place first.
Put a good rear tire on the rim, like a Specialized Armadillo or Schwalbe tire with Kevlar liners keeping both at 1.95 or so, or similar tire.
Forget the Slime stuff and tape the spoke nipples (which I did not do, but I do not motor much).
And, you will need to make up a longer throttle cable for any CF frame - also discussed on this site - but not for Treks or most cruisers. (Trek has some nice cruisers that have two brakes and gearing.)
And, do not be afraid to haggle on new bikes...even if it a seller's market at the moment.
Total cost? About $950 or less: $550 for complete engine kit, $100 for wheel, $250 for bike, $50 tire and misc.
Keep it simple and have fun.
