I went the mtbREVIEW website to try to find out if it's important for cyclists to shave their legs. James Peterson from Salt Lake City, Utah, posted information on this.
James begins with the assumption of a cyclist that rides an average of two hours every day, six days per week. Any rider of this caliber, he points out, is bound to be in very good shape. Shaving one's legs therefore would accentuate one's leg definition, making the person subsequently more attractive and aiding this person in getting "more Bettys."
Not wanting to ignore the more traditional reasoning, yet still relegating it to the status of "the less important reason," is that shaving one's legs in case of accident. Listing such potential hazards as falling on one's knees, bashing one's shins against a rock, and getting scraped by dead branches near the ankles, James points out that bloody-legged activities usually require that one later clean dried blood out of one's hair afterwards. James claims, "This hurts a lot." Mountain bikers are oft-prone to leg injuries, and anything that makes cleaning the blood off, in this case, removing hair before hand, is a good idea.
James summarizes by saying: "But mostly it's all about good looks and getting girls."