The Radial 34 swallowed all of my stuff just fine - clothes for work including jeans and sneakers, a change of cycling clothing for the trip home, my 13" Macbook Pro and charger, and a rain cape. I especially liked the separate shoe compartment, although fitting a pair of size 10.5 Asics sneakers was a little tricky. But the pack is poorly designed for bike commuting in anything but the most upright or straight-backed riding positions. As soon as I start to bend over the handlebars my spine starts digging into the rear of the pack. This is because (1) the rear of the pack is where the laptop compartment is positioned, (2) there is little padding on the rear of the pack, and (3) the rear of the pack is not curved. This means that the AirSpeed mesh stretches very little before it bottoms out against the rear of the pack. On my Manta 36 (and, I suspect, other AirSpeed-equipped hydration packs) the rear of the pack is curved, allowing the mesh to stretch to the point of actually providing support before bottoming out. This curved back, however, makes for a poor laptop compartment. Nonetheless, going forward I am going to use the Manta. I can pack my clothes and shoes in the main compartment so that the soles of the shoes face away from my back, and then shove my MBP (in a thick sleeve) into the stuff-it pocket. That way the MBP effectively rests against the soles of the shoes and the clothing in the main compartment. So...swing and a miss on the Radial 34. I wanted to like it, but it just doesn't work for me.