The bicycle ride you love may actually be damaging to the nerves of your penis. Prolonged riding can decrease the blood flow to the base of the penis because of added pressure to that area, called perineal vascular compression, to the area caused by the saddle of your bicycle. This transient numbness, lasting anywhere from hours to days in most cases, usually affecting riders who go greater distances more often that others.
Older men are also more at risk because of decreased elasticity in their blood vessels.
When riding for long periods of time take frequent breaks. Get up and out of the saddle often. It's easy enough to remember. Also change your body position frequently during a ride. If you're crossing railroad tracks never remain seated for taking the actual tracks.