So what is a mountain bike? Some would say it's a self propelled, wheeled vehicle designed to go wherever the rider wants to and have fun at the same time. I hope this isn't too obvious, but in order to answer the question, you really need to know what you want. I can think of a load of other definitions based on which bike is fastest or lightest or some other scientific measure, but these yard sticks have proved un-helpful in the past. The lightest bike will break the moment you start having real fun. The fastest bike uphill is more uncomfortable than a hair shirt. The fastest bike downhill only goes uphill if you have legs like Arnold Schwarzenegger (or a lift). Perhaps you can see where I'm coming from, there are lots of specialist bikes out there but unless you have a limited riding style they're very limiting indeed.
