According to a study in the Journal of Sexual Medicine, it all hinges on the position of handlebars. The study's author offered this terrifying explanation: "Modifying bicycle set-up may help prevent genital nerve damage in female cyclists. Chronic insult to the genital nerves from increased saddle pressures could potentially result in sexual dysfunction."
Specifically, handlebars that are placed lower than the seat of a bike seemed to increase pressure on the genitals, eventually decreasing ability to feel sensations. There, is that detailed enough?
Now excuse me while I go and gloat to all my friends who've been telling me to just "give it a try around the neighborhood to get comfortable with it." Please. At this point, I would sooner rollerblade.