This pint-sized seat bag from Detours won't weigh you down and has just enough room for the essentials. You can carry a spare tube, patch kit, tire levers, keys, credit card and even an energy gel! Thanks to its compact size, though, it fits neatly under your seat and out of the way. If you have even more to bring along, this versatile bag unzips to swallow even more stuff. And, it attaches easily and securely without tools.