Just depends on the mountain bike - I have an old Klein rigid framed mountain bike - it does have a suspension fork; but because it is an aluminum racing bike, it is very light, very nimble and I just put narrower tires on it since I had to replace them anyway. You can also buy mountain bikes without suspension forks (rigid forks) and can be pretty light. I myself prefer a bike that is quick handling so I would prefer my mountain bike over a hybrid for that reason.

So, all mountain bikes are not always heavy, cumbersome and slow. Just depends on what you particularly like and what you want to afford. All of that said, I would recommend Breezer bikes if you are just looking for an all around commuter.

spoke