Originally Posted by specialmonkey

Some packs have systems that will keep it off your back, along with ventilated straps, it can reduce the sweat factor.

The one I bought has such a system called Airspeed. I bought the pack at Wiggle (cheaper), based on the following youtube review:

https://www.youtube.com/watch?v=uN1v4HuL3JE

The Airspeed system does seem to work. I'm much less sweaty than when I used a Crumpler pack that didn't have a suspension system.

I'm still a little sweaty after an hour commute, especially as temperatures start to rise.

My shoulders seem most affected, as that's where the pack rests, and doesn't ventilate well.