I am one of the hopelessly unrepentant junker builder types. The bike I just rebuilt again see http://motorbicycling.com/f15/just-too-376.html
The bike has a 26" cruiser frame, but the front wheel is from the huge mountain bike I had laying around. The rear wheel is from a twenty inch girl's bike. The handle bars are from a different girl's bike. Ir has front brakes from the huge mountain bike as well.
The twenty inch wheel I had to pull from the sissy schwinn so of course I either had to junk the schwinn or find a rear coaster wheel. Enter a 16 inch bike wheel I had laying around. So the sissy has a 20" crank set a 24" frame and front wheel. but full sized sea from the huge mountain bike. I set the sissy up with a 350 watt electric motor as well as all the other mismatched parts.
I made a decission today. I am not going to deal with a bike shop again. Not their fault but you can't make chicken salad from chicken droppings. Best to just chuck bike parts that aren't right to begin with.
Anyway it's fun to cobble together bikes.