Originally Posted by
blamire
take a bottle, get a jersey and stuff all your other stuff in your back pockets. trust me, when things heat up and you've got something on your upper back stopping a lot of heat from escaping and making you sweat big time, it ain't pleasant.
I have had the opposite experience. I only use a hydration pack in the hottest part of the summer. I fill the pack with ice and freezing cold water. This makes the pack cold. So, you have a cold pack against your back, but I guess it depends on how far you ride. I was only doing 30 mile rides with this hydration pack.