The real beast is air friction once you've gotten to the speed you want to maintain. (unless you ride a Huffy) All other forces are neglible by comparison. As far as the rest, I forgot the equations but for an example let us say you have a choice between 2 20lb bikes on the first the frame weighs 10 and each wheel weighs 5. On the second the frame weighs 15 and each wheel weighs 2.5. Now both bikes weigh the same but you'll be better off with the heavier frame and the lighter wheels. (Unless it's a Huffy)