Depending on the type of riding you prefer there is a bicycle specially designed for that style. It can be said that there is not one bike that can do it all. Try taking a road bike down a mountain trail and you will not like the results. And although a downhill bike can assuredly supervene the trail of a road bike, it will not do so very effectively.
There are three major categories of bicycles, road, mountain, and hybrid. Each of these categories will have sub categories supplementary defining a specialized role. And even then these sub categories can be broken down into dissimilar types as well. A good example of this would be a mountain bike in the all mountain sub category falling into one of two dissimilar types, full suspension or hard tail.
Road bikes are the easiest type of bicycle to explain. They are meant primarily for riding on hard paved surfaces. The frames are very lightweight and stiff. A stiff frame equates to a very responsive ride without the soft feel that you would feel in other types of frames. There will not be any suspension on a road bike. The tire will be very narrow and pumped to a high pressure of over 100psi.
