go for it. buy/scrounge the cheapest crappiest parts if you want. the best way to learn about bikes is to do the work yourself, instead of looking over the shoulder of your local bike shop mech. Mount that 120mm spaced wheel and see if the axle is long enough to make it yourself.

Don't listen to these city slickers that take their bikes in to the shop every time because they want the job "done right" and don't have the time or tools. Do it wrong, get the tools, and LEARN from your mistakes, be self-reliant and independant. And what better vehicle than a cheap bike is there for this?

don't mind me, got up on the wrong side of the couch this morning i guess.