maybe it's for the better

Bicycling.

Bicycling has been linked to impotence in men and also may affect the sperm count. Pressure from the bike seat may damage blood vessels and nerves that are responsible for erections. Mountain biking, which involves riding on off-road terrain, exposes the perineum (the region between the scrotum and the anus) to more extreme shocks and vibrations and increases the risk for injuries to the scrotum.