I absolutely love my Dakine Apex backpack. It looks awesome. It's small, but can easily handle very large loads. It's a cycling specific pack, so it fits properly when riding a bike. It has a dedicated helmet holder. It's made for mountain biking, so it's durable as all hell. The waist belt is removable. It breathes well. It also ships with a hydration bladder, which I can install when I go mountain biking. It has tons of pockets, both inside and outside. This pack has been refined continuously for years, and it shows it. A very well thought out pack. Between the helmet pocket and the lashing straps on the bottom of the pack, you wouldn't believe how much this pack can carry when needed.

http://www.dakine.com/bike/packs/apex/