Do I need a women's bike?

Standard bikes are built based on male physiology. Women's bikes are proportioned to suit the general female population, and most have components to suit women's anatomical needs, such as shorter-reach levers for smaller hands. A few companies even tune frame tubing to suit women's generally lighter bodies. All of this leads to a significant if obvious benefit improved fit but it also makes you a better, more confident rider. 

The longer cockpit of a standard bike often causes female riders to stretch their torsos and arms, as well as move forward on the saddle. This makes getting a secure grip on the levers more difficult, but it also moves a rider's center of gravity too far forward, compromising balance, mitigating power output and removing some rear-wheel traction. None of this is good.