Mountain bikes have evolved over the past 15 years, from do it all rigs, to the many variations that we see today. There are four main categories: cross-country, downhill, freeride, and dirt-jumpers.

Cross-Country:

Cross-country bikes are where mountain bikes started. These machines are designed for trail use, and will see a variety of conditions. Typically they are on the lighter end of the weight scale. They usually feature geometry that is suited towards easy climbing and moderate decending. They usually have three inches of travel in the suspension fork, and the same in the rear if both ends are suspended. This is rrelative to the size of bumps and jumps that you would run into on a typical cross-country trail.

Downhill:

A downhill bike is generally a full-suspension rig, with a 6-8 inches of travel on both ends. The frames are built to take a lot of abuse, and the components are selected on the same merits. The geometry of the frame is very laid back to allow for the riders weight to be shifted rearward. In order to keep the chain in place on rough courses, a chain guide with a single chainring is used up front, restricting the bike to mainly downhill use.

Freeride:

Freeride bikes are a mix of cross-country and downhill bikes. They are front or full-suspension bikes with travel ranging from 5-7 inches. The geometry varies quite a bit, as some freeride bikes are more cross-country oriented and others are more downhill oriented. The angles are based on the amount of travel, and if climbing is part of the bikes purpose. With regard to components, again, if the bike is going to be used for climbing, weight will be kept to a minimum, otherwise, the beefier the better.

Dirt-jumpers:

The newest trend in mountain bikes are dirt-jumpers. These bikes are designed for just what their name implies. They are beefy frames, with slack-ish angles, and usually just a single chainring and chainguide up front. Front suspension is common, with 3-5 inches of travel. These bikes tend to get crashed a lot, so they need to be built very strong, hence they tend to be on the heavy side.