Originally Posted by
asmac
Esp. important are the disc brakes... stopping is as important as going when you need to stop and greater inertia needs better brakes.
Disc brakes are really, really nice in the rain. But rim brakes have just as much stopping power when your rims and tires and the road are dry. My last two bikes had disc brakes. I loved them, and was sure I'd never go back. One day, while my bike was in the shop, I test rode a high end racing bike to pass the time until they fixed mine ... and almost crashed because its dual pivot rim brakes had so much more stopping power than I expected, having got used to Avid BB7s.
Anyway, I wouldn't worry so much about a mountain vs road bike, because almost any frame will hold your weight. It's the wheels you need to be concerned with.