Rash from Bike Shorts

[Catrin]

I started seriously riding this summer. The problem I'm having is that the last two times I've gotten off the bike after longer rides, I have a terrible rash on my thighs right where the bike shorts start above the knee, going up my thigh about six inches. It is not at all itchy, but red, raised and blotchy. Does anyone have any idea what's causing this? Thanks

Sounds like a heat rash to me, I had this problem last year though not this season (and I am wearing the same shorts).

Are you hydrating enough before/during your rides? Are you riding in the heat of the day? At least for me it happened when I simply had to ride during the hottest part of the day.