Image source: http://www.giant-bicycle.com
Race bicycles are by far the fastest and lightest of all types. They have one purpose in mind, offering the most performance they can be. That is, to use the cyclist energy to its maximum and minimize energy loss. For such bicycles, the frame is usually made of allows like aluminum or carbon. Like we saw in previous sections, the frame must be the lightest it can be, while being the stiffest possible. By stiffest, we mean a frame that does not bend too much when submitted to external forces. These forces can come from various sources. The cyclist is one big source of stress on any bicycle. Every time he pushes on the pedals, the whole frame will inevitably bend to some extent. The road disparities and imperfections will also induce high energy stress to the frame. The more the frame bends over these forces, the more energy is dissipated by it. If the frame dissipates energy, this is fundamentally bad because that energy is lost instead of ending up pushing the bicycle forward.
There are other subtle things you can notice on frames that will give you valuable information on its quality to be a good race bicycle for example. The distance between the seat tube of the frame and the rear tire is one of these. The closer the tire is from the seat tube, the most efficient your race bicycle will be. It will be efficient in term of transferring more energy into motion. It does so by making the frame stiffer and more aerodynamic. Keep this in mind as we go along and look at other types of bicycles. You will see great differences of this tire to frame distance. You will notice that bicycles that are less performance minded will have great tire to frame distance. These bicycles do not need it and it makes it probably easier to make them as well.
Let's talk about the sitting position now. Observe the height of the saddle and the steering handle. On a race bicycle, the sitting position is favoring a more inclined position. The cyclist must offer the least air resistance as possible. The result of this is a quite uncomfortable position. This is obviously not made for everyone. Needless to say, it requires a good muscular tonus from the cyclist, especially in the back dorsal regions. Even then, it usually feels quite painful for the first few rides of a new season, when you haven't ride it for a long period of time.