Lifelong cycling here who recently bought a new bike. Because of Covid, I’m unable to get set up for a bike fit until at least late fall. After a few minor tweaks, I feel like I’m pretty comfortable on the bike, but am experiencing regular chafing on both gastronemius muscles right below the back of my knees. Any ideas on what might be causing this? It’s summer and I’m extra sweaty, but I’ve never experienced this problem in the past. Very strange.
Maybe it’s you shorts? Have you tried different shorts (different length, different seams, different material)? Also, are your thighs rubbing on something, like a saddle bag?