I am looking for a backpak to commute about...
I am looking for a backpak to commute about 15-20 miles on bike. need to carry change of clothes, shoes, lunch, maybe some incidentals any suggestions
This is a great pack, but I would go with something a little larger, such as the talon 22. Another great commuter pack I would recommend is the osprey flapjack, it's less versatile, but if you want to bring some books/papers/a latop it's an awesome bag.
Another awesome option: http://www.backcountry.com/osprey-packs-metron-25-hydration-pack-1320-1500cu-in
The metron is about as awesome as they get for smaller commuter packs.
You definitely are going to want something a bit larger for carrying that much stuff. Check out the Osprey Momentum series. They've got some really cool bike-commuter specific features.