I have the Alterra, which appears to be a smaller (28 oz) version of the Flashflo. (see Camelbak site - I bought mine at REI). I only use it for running, not biking, and 28 oz is enough for me to run for 90 minutes or so in the North Carolina summer heat. I compared it to bottle-packs and found the Camelbak was the least bouncy. It also has a soft lining, unlike some bottle belts, which is important because it invariably rides above the waistband of my shorts to rest against my bare belly. I cram my tiny mp3 player and a gel into its nooks and crannies, but there is minimal storage. The tube wraps around the waist and clips in place, but it also came with a clip to attach to your shirt if you prefer. I highly recommend it for running - probably not enough capacity for cycling though!