Messenger bags are great, but with two straps to distribute the load, a backpack is often a more comfortable option for longer rides or heavier loads. Unfortunately your options have either been student backpacks that leak like a sieve, sit up too high, or cost a fortune. We designed our backpack with a full welded waterproof liner that is removable and replaceable if it is punctured. 1500 cubic inches. ** Newest accessory pouch version fits phones (or phone inside a case) up to 5.25" x 2.75" x 0.75"