Here’s a fun brainteaser for you:

While I was changing a flat tire by the side of the road Somewhere In Wyoming this summer, my buddy Clint posed me an interesting question that thus far has us stumped.
When Clint rides his road bike, he carries a CO2-canister tire “pump”. It’s basically a little CO2 canister with a trigger and a valve connector on it, and he carries it because it’s lighter, quicker, and smaller than a hand pump.

However, something weird happens when he uses it: by the end of the ride, the tire he inflated with it has lost pressure. This doesn’t happen with his floor pump, and when he pumps the tire back up with the floor pump when he gets home, it stays inflated on his next ride without losing pressure.

I’ve proposed a couple of things for why the tube might lose pressure, including:
1. the CO2 pump can inflate the tube quite quickly, and this might stress the rubber, creating microcracks in it. Over the course of several hours, this might cause a problem.
2. the CO2 is quite cold when it enters the tube, because its been under pressure and is now expanding. Cold makes rubber more rigid, so very cold gas entering the tube might again put the inner tube at risk for cracking, even if it’s being inflated slowly

However, those mechanisms a) are suspect, and b) fail to explain why the tire should then maintain pressure after being reinflated with the floor pump

What say you?

Just got a full set of BD C4 Camalots, and I was inspired:

Oh ye Cams how I love thee.
With thy braided stainless steel cables
and thy precise double axles.

Oh ye Black Diamond
Thy minions are legion.

Kind of makes you teary-eyed, huh?