Osprey's Viper 13 is the right choice when you're out for a big ride in the mountains or the Desert. You'll pedal in comfort with the foam frame sheet spreading the load across a ventilated mesh back panel. The stretch shoulder harness provides a contoured fit. The webbing hip belt is removable to shave ounces while upper and lower side compression straps offer additional stability if you're carrying extra weight. Access your gear in the main compartment via the zippered front panel. You can slip small items into the dual side mesh or harness pockets or stash a layer in the front fabric Shove-It pocket for quick access. There's even a scratch-free slash pocket for your shades. Bike-friendly features include a hydraulics lt 2.5 liter reservoir with magnetic bite valve retention, internal bike pump storage loops, and osprey's innovative lid lock helmet attachment system.