Originally Posted by
dwolsten
For higher-end road bikes, there's a bigger difference than just paint colors: the geometry is different, to account for the typically-different proportions that women have (usually shorter arms and torsos). My bike, the Specialized Roubaix, has a women's counterpart called the Ruby. It's identical in every way (including price) except for paint colors and geometry of the frame (and the fact that it comes in smaller frame sizes). If a women's frame fits you better, then go for it. Honestly, I like the color choices on the Rubys better anyway; the men's bikes tend to have pretty boring color choices. But I'm over 6' with long arms, so there's no way a women's bike is going to fit me well.
"Gender specific" geometry is generally just a guess based on pitting the "average" woman vs. the "average" man. As in all other fit issues, no one is actually average, and virtually everyone diverges from average in one or more aspects, so it's completely unsurprising that some men would find "women's" bikes a better fit and some women prefer "men's".
After WWII, the Air Force figured out that a huge number of crashes during the war were caused by the cockpit being designed for the "average" pilot, which in practice meant that it was poorly designed for everyone.