Quote Originally Posted by GLC1968
See...this is exactly what I expected to hear from my derm! (I never went because I think I've figured it out...)

Based on some experiments I did...I've come to the conlcusion that the welts are hives brought on by overheating. It's not really a heat rash in the traditional sense, but it's definitely from the heat. A few weeks ago we were on a 75 mile ride and right at about mile 45 or so, the heat got intense (we'd left late so it was mid-day right when we hit the farm land....no shade). It was well over 100 degrees on our bike computers and I just wilted. I felt it come on with a slight tingling in my whole body and sure enough, I glanced down and the hives were appearing. It was a very rough ride and while I was amazed at my ability to stick it out, it did a number on my legs. Those hives took DAYS to go away and now, 3 or 4 weeks later, I still have the discoloration from them.

The good news is that on our next long ride (78 miles), I ran a little experiment. I knew that our planned ride would take us by plenty of stores, so I could be liberal with the water. I carried extra, wore a ton of it, drank more than usual, and did everything in my power to keep my core temp down. I was dumping it on my head and my back almost the entire ride. It worked..it was just as hot for that ride as it was for the other one (and the second one was even more hilly) and I felt good the whole time AND saw no hives. They were kept at bay!!

For me, it's definitely heat-induced and not just leg heat...but core body temperature heat! I'm just happy that I now know how to control it.

That makes a lot of sense. I have not had these sores on my legs the entire summer until the last two weekends (Dallas has had 100+ temperatures for couple weeks now). Last Saturday, when I was out riding, it was 100+ degrees. For the most part I felt fine, I was taking frequent water stops. But the last part of the ride there was absolutely no shade and it was mid afternoon (I obviously did not get my butt out of bed early enough). I was starting to feel my body over heating (I was hot but had chills, exhausted all of a sudden, sleepy). I remember looking down at my legs to pour water on them and I noticed the rash.

Thanks for the information!!!! Note to self: Don't press snooze for two hours - get butt out of bed to get the ride done in the morning!