Your chafing can be an indication of an incorrect bike seat. According to Mary Paterson of Women's Cycling.ca, "The ensuing chain reaction of poor posture to relieve the pressure from an uncomfortable saddle can lead to neck and back pain and can alter how the whole bike feels." A seat that is too wide, that sits too far forward or that is tilted at the wrong angle can leave painful red chafing in your inner thighs or underneath your pelvis. Try out as many bicycle seats as you can, using demo seats at your local bike shop, until you find one that suits your proportions perfectly.
Cycling shorts use a padded chamois inside of a tight-fitting spandex short to provide an extra layer of protection between you and your saddle. A padded chamois can be made from foam, gel or even leather, and prevents both rubbing and soreness from impact and vibration. A pair of cycling shorts is supposed to fit tightly to prevent movement while riding, which can cause chafing. You can always wear it underneath your regular clothing.
Butter Your Buns
Chamois butter is a special lubricant designed to prevent chafing in cycling shorts, and is one of the most effective remedies for chapped cheeks. Look at your local cycling shop for cycling-specific products, or look for an anti-chafe balm at any sports store.
Perspiration on your skin can cause it to stick during your pedaling stroke, accelerating your chafing. As final protection from cycling-related rashes, try to keep yourself dry during your ride. Wearing a thin moisture-wicking liner short inside your cycling shorts can pull perspiration away from your body, and dressing appropriately for the temperature can prevent overheating and excess sweating. In addition, using baby powder before your ride can help mitigate the chafing effect of wet, clammy skin.