Just coming back to this. There are a bunch of things you can do to get better at mountain biking, and I kinda think of it like skiing where you have a local 500' vertical hill but maybe I think I'm "too good" for it. I always go and try to improve technical things rather than hanging on. So think of these exercises as that type of scenario.
First off, good mountain biking requires moving your weight around on the bike. I have no idea what level you're at so bear with me. Pick a flat piece of road and practice moving your weight to the back of the bike and lifting up the front wheel at the same time. Sort of a mini-wheelie. Most people can get the wheel up...practice doing it smoothly..no banging..and for more distance. Then do the back wheel..little endos..same drill..weight forward, pick up the back wheel. You constantly have to do little wheelies and then little endos to get over roots and rocks. This is a basic skill. After the flat road, try doing it up and down curbs..increase your speed..angle of attack. You should be fluid and at ease while doing this over a curb with no damage to the bike! :-)
Depending on what you're riding (terrain), brake modulation is very important. Your front brake is almost always where most of your braking power is, regardless of how steep the terrain is unless you're going seriously uphill obviously. Practice hard braking on loose surfaces. Dirt road..whatever. Then find a very short, somewhat steep hill..a mound if you will..where you can minimize crash damage. Practice modulating your speed carefully down the hill. A lot of people have this thing about going over the bars when braking. That CAN happen..but you will stop braking naturally when you get to that point. For the most part, you're not going over the bars. Keep braking harder and you'll get a feel for where the rear will lock. The rear will slide down the hill..straight down..and that can help you as well as hurt you. The front won't lock for the most part..you'll eventually get to the point where you will feel like you're going over the bars and you'll let go of the brake. Same thing, get used to that feeling. Eventually you'll get used to how much brake you can grab front and back before you're in trouble. Going back to the first point, moving your weight around..when braking hard, moving your weight back will stop you from going over the bars and even out your weight for better braking control.
I can't emphasize this enough, you cannot be rigid when riding. Like skiing bumps, you have to float..constantly move your weight around. Find the sweet spot..
Here's a good video..it's a "downhill" instructional..but ignore that..the position is the same for most technical riding and it really has good slow-mo of the "float" required..absorb bumps..move your weight around..
Someone above mentioned keeping your momentum going..this can help you..moving forward keeps you upright. However, there will come a time when you are best served by stopping and not bothering to try that next bit just yet. You'll know when that moment is. No hurry..it's a life long learning curve. :-) To elaborate on this a bit, if you have obstacles perpendicular to the trail, speed is usually good. The wheel rotation will keep your rolling. In general, the show-stopper, literally, is when you don't have enough momentum to get over the next bump so to speak. If the front wheel hits a rock and you stop dead, you'll go over the bars. So you have to decide, do I keep my speed up and ride that stuff out? Or do I stop and walk over/around it. Crashing on rocks is not fun, so I'd work up to it slowly. :-) Parallel hazards to the trail can be tricky. There is a trail near here that is basically rock outcrop with "ruts" or grooves in the rock. If you get railed into one of those and it narrows up, it will stop you dead and again, over the bars. Notice the common theme of rocks here.. :-) Having said that, smooth rock a'la Moab, can great fun with all kinds of traction.
Climbing seems fairly obvious..and it kinda is..but rule 1 is keep your momentum going. If you slow down too much you'll stop being able to roll over bumps and you'll just fall over. Rule 2, the steeper it is, the closer to the stem your face should be. And the seat point will eventually be jamming up your butt! The closer you can get your body to the top tube, the steeper the terrain you'll be able to climb. One problem is this position starts to limit your ability to move around and stay upright. That's a call you'll have to learn to make.
I'm sure there's more that I've missed.
Edited by Scott43 - 5/21/14 at 8:29pm