Check out Deuter. I've been using a "Giga Bike" daily for about three years and it's held up perfectly. It might be a little large for you (28L), but they hav

Check out Deuter. I've been using a "Giga Bike" daily for about three years and it's held up perfectly. It might be a little large for you (28L), but they have a few smaller models, and compression straps help somewhat. I particularly dig the "airstripes" design, which 1) suspends the pack away from your back to minimize the sweaty shirt effect, and 2) provides the right amount of friction so the weight isn't all on your shoulders.