The main reason we are all here, but why so many choices? As a general rule look at the tires; a wider tire is better for off-road uses where traction and bump absorption are required, while a narrower tire is better on hard pack surfaces and pavement because it will roll faster. Also look for the riding position, an upright position is comfortable and relaxing, but the wind hitting your upright body will slow you down. The more leaned forward you are the faster you will go because you are lowering your chest out of the wind and allowing your legs to use more powerful muscles. Here are some general categories to start looking at.