Depends on the ride, but for the most part I've adapted water bottles to the purpose. I can get a full length box wrench/pedro allen, tube, C02 inflator, two spare cartridges, Leatherman mini, patch kit and other assorted odds'n'ends into a ~32 oz bottle. Usually it's a Gatorade squeeze bottle in a Cateye cage or a Zefal Magnum in a Profile or standard cage.
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This is Africa, 1943. War spits out its violence overhead and the sandy graveyard swallows it up. Her name is King Nine, B-25, medium bomber, Twelfth Air Force. On a hot, still morning she took off from Tunisia to bomb the southern tip of Italy. An errant piece of flak tore a hole in a wing tank and, like a wounded bird, this is where she landed, not to return on this day, or any other day.