shaving your legs, arms, or both?
For cycling, there are only a few reasons to shave:


Massage - feels better without all the hair tugging.
Taping/bandaging - In the event of a crash, taping and bandaging is easier without hair. Additionally, wounds in general are cleaner when incurred without hair.
Vanity - Hair tends to cast shadows and blur the edges of well defined muscle.
Cooling - Hair is an insulator, so especially hairy individuals will shave for the cooling effect.


There are some sports where shaving is done for performance purposes (chiefly swimming), but anyone that tells you that in cycling is fooling themselves. My personal experience is that crash scars heal better and are less visible when shaved, but that may be an individual thing.