It wasn't a bonk, since I was able to keep my heart rate up. It was a lot of overall discomfort that I attribute to the heat and not having enough to drink. My legs were aching pretty badly on the last climb up Mt. Hamilton, and they were starting to cramp up. I also noticed that I had stopped sweating about half way up the climb, even though it was quite hot. I was also getting chills, never a good sign.

I was drinking one large bottle of Cytomax per hour, but I don't think that was enough for the hot return trip in the afternoon. I'll have to try the ride again soon to see if I can manage it better.