Originally Posted by HammerTheHill
One thing you can do, and I fell into this habit when I switched from road to mtn, is lower your saddle. Without even thinking, I'm sure you have it pretty high in order to get the correct amount of leg extension. This is great when your pounding on some easy single track or a fire road but when you get on technical downhills or just plan technical riding, you need to have the saddle down and out of the way a little bit so you can move your body weight around.
I think he'll feel a little more akward with the seat really low, coming from the road...maybe drop it a little, but going slammed seat right away is gonna throw his balance off a little (or at least it did for me in the beginning).