I commute by bike (24 miles average per trip). I decided I needed to upgrade my backpack. I got my backpack yesterday. I test packed it with my normal commute items Lots of room leftover for other stuff including lunch. Honestly room enough for a few grocery items or take out on the way home. The upper outer pouch fits my u lock and cable easily. The bottom pouch is roomy for tools chain and the like. A foldable tire might even fit. The zip pounces behind each pouch previous mentioned pouch are roomy as well. The upper one will fit a kindle and/surface maybe both. The bottom a small book or the like. The yellow rain flap is awesome. The Velcro for the laptop pouch is nice. I am thinking about purchasing the optional pouch for that. When I put it on and adjusted the straps I thought WOW it feels like a part of me. The zippers are solid. It has a solid attachment point for a taillight. There are Lots straps and tie down points. Both the waist belt and sternum belt are comfy. Velo Transit did a great job