Originally Posted by
due ruote
If you're willing to go with friction shifting and limit yourself to 7-speed, all you really need is a 7-speed freewheel and perhaps a fresh chain. No need for new wheels or anything else.
i agree; if the wheels are fine, and you don't weigh enough to worry about the axle, you can get new chains and freewheels in 6 or 7 speed flavors with ease, and very cheaply. Otherwise, the cassette hub in the back is a good idea.
-rob