In the middle so you can adjust it when needed
Both.
When you're braking hard, trying to climb a steep hill or turning hard.
The brakes use friction to stop the bike and the tyres use friction to grip the road.
friction
If you want to buy a cool mountain bike you should go check out: chainreactioncycles.They got a large choice of different mountain bikes in different coulors and models.
Mountain Bike Rally happened in 1994.
Friction is what ultimately stops your bike
A road bike is faster on the road than a mountain bike. That's all
it really depends what kind of mountain biking you want to do. if you are doing it seriously or just for a bit of fun. you should go to a bike shop and tell them what you're going to do and they should recommend bikes that would suit you. hope it helps :)
Mountain bike magazines focus on mountain bike tracks, tips and information regarding bikes in general as well as helpful tips about bike parts and repair.
Friction. Air friction, road friction and mechanical friction.
The tyres and portability. Mountain bike has to be lightweight and easy to carry around, we usually recommend foldable ones. Tyres are important as well,