I did a solo century in the 100s, it topped at 116 F around 2pm. Stupid, yes. Educational, yes. Yeah, it's fascinating to watch your heart rate "kite" if that's the correct technical term. It felt dangerous around hour 5 so I found a nice shade tree and took a 40 min. rest/nap, and let water assimiliation catch up. When it's that hot, it doesn't seem to matter how much you drink if you're riding, you never catch up hydrate-wise. I don't think I'd do it again, but I think the body is alot more resilient that we give it credit - but it wants to be listened to..and its' issues addressed.

I hit 192 spinning last night, close to maxed-out.