Also, because many mountain bikers are after thrills and speed, their tires cut into the ground. Slamming on the brakes after zooming downhill, sliding around sharp corners, and digging in to go uphill: I see the results of this behavior weekly. …
I don't see how our tires "cut" into the ground; no more than horseshoes to say the least. And we all know how we all love to bomb down a hill and drift around corners, and spin out the rear wheel on purpose while climbing.
