Wheel truing is actually something that is very easy to do.  Even if you have no experience with mountain biking or truing a wheel, it doesn't take a rocket scientist to accomplish it.

The first thing to do is make sure that none of your spokes are loose.  To check, grab each spoke in turn and try to shake it back and forth.  If the spoke  wobbles, or makes pinging and grating noises, it's loose.  If it's loose, add tension to the spoke by turning the spokey anti-clockwise with your finger and thumb pressure.

Keep turning and shaking until the noise is gone and the spoke doesn't wobble or move.  Move on to the next spoke until you've gone all the way around the wheel and checked them all.

Now, it's time to see just how true the wheel actually is.  Turn your bike upside down then spin the wheel to see where it comes closest to rubbing on the brake. 

As a sport or a hobby, mountain biking can be split into 9 different categories.  These categories are very versed in what they offer.  They are:

1.  BMX

BMX is a style where the bikes offer 20 inch wheels. These bikes are commonly used at skate parks or with dirt jumps.  Because of their smaller wheels and shorter wheel bases, BMX bikes are much easier to perform tricks and stunts with.

2.  Cross country

This type of mountain biking involves riding your bike up and down hills.  Although it's the least extreme form of mountain biking, most cross country riders are very fit and go on long rides. 

3.  Cyclo cross

This is a cross between road and mountain biking. These riders have to go over obstacles, cross through rivers, and race on and off the course.

4.  Dirt jumping

Dirt jumping involves jumping the bike over large man made dirt jumps then doing tricks while they are in the air.  These jumps are normally close together so riders can go over six or more jumps in one run, gaining a flow to give them more  speed for bigger jumps.