Originally Posted by
DrIsotope
...to a point. It is currently 109º outside, with a nosebleed-inducing 6% humidity. We're in an Extreme Heat Advisory until 9pm tomorrow. I would not recommend to anyone that they should go ride right now. There's nothing to acclimate to out there. You have to severely moderate your intensity, 50oz of water won't last an hour (might not last half an hour) and with such a low RH, there's no real way to gauge how much you're sweating because it's evaporating so quickly. Riding outside of where I'm sitting at this moment, at anything beyond a soft pedal, is physically dangerous.
I'd have to disagree. I've done long pass climbs in 104°, low RH. No, you can't keep up with the water losses. One has to rest and hydrate tactically. I've gone through 70 oz. in 20 miles. It's not true that you can't climb decently, but one has to be acclimated to it. No, it's not dangerous if one knows what one is doing and knows the signs of overheating. I watch 2 things: HR and forearms. If HR climbs unreasonably, stop in the shade and drink. If one's forearms become dry, same. If one is riding in a desert with no shade, take plenty of water and a portable shade. People ride across the Outback. Acclimation greatly reduces water losses.
Ever take sauna? I've done in 100°C.
Start small and pay attention.