rear wheel is crucial. I have a "redux" schwinn twinn. I changed almost everything in an effort to lighten it up (all with free parts from other bikes). One of my upgrades was to a 6 speed cluster on the back. I am quietly (cheaply) looking for a 40 hole hub to build a back wheel back there. But I spend 130 on the bike originally and have gotten hours of fun, and I am proud of how much better it rides now. It was a 1979 with a lot of rust to the components and wheels, but the frame was in great (if heavy) shape. The only other drawback is the whippy!!! frame. But it has held together so far. I also had to bodge a brake drop from the fender arch for the rear, I made this from heavy metal. The timing gear is on the right with the crank ring it is a 14-30 in the rear and 46 up front for a nice choice of gearing and will HAUL down the hills anyway!