Water and heat during unsupported solo rides are tricky.
Did Washington Pass from the east yesterday. When I started in Winthrop mid-afternoon it was 95 degrees. Moderate headwind all the way up to further help dry me out, but the temps obviously got more manageable as I ascended. Still my 2 bottles was woefully inadequate. A friendly motorist gave me a liter at the overlook at the pass, and off course the Mazama store helped out on the way down.
I can see adding another bottle somewhere on the frame (3 total), but riding with a Camelbak is not something I would like to aim for. Hmm, what to do?