
The mountain bike frame is the main part of the mountain bike and all the other components and parts attach directly to it. There is a top tube, seat tube, head tube, down tube, fork, chain stays and seat stays. Full suspension models often have a very irregular design that doesn’t look anything like the double triangle common on hard tail bicycles.
The mountain bike frame can be made from a wide variety of materials. On the low end of the spectrum is steel which is cheap yet still strong and much softer than aluminum. Some people prefer an incredibly stiff frame, while others prefer some give. Aluminum frames are incredible stiff, but carbon fiber frames can be much stiffer than that, although they are often prohibitively expensive.
A mountain bike frame should be strong and light for the best results, but most importantly it should fit the rider very well. They shouldn’t be hunched over, or too up right although each rider often has their own preference on riding angle. The pedals should be easy to reach and mounting and dismounting the bike should occur with ease.