The valve cap… yes, that small piece of plastic that screws onto the valve, apparently useless, that almost always ends up lost somewhere in the world.
The truth is that if your bike uses Schrader valves, the caps really are useful, much more than you think.
Their main purpose is to help keep dust and dirt out of the valve. Even that may not sound like a particularly glamorous job, but if particles get jammed in the sealing surfaces, your tubes will develop a leak. They can even get clogged enough to not allow a proper connection with your pump.
A dirty valve degrades and loses air much faster. If you’ve ever had a tube with a slow leak, that seems to hold air initially but loses pressure rather quickly, it’s most likely a leaky valve. Once the valve is compromised, there’s nothing you can do but replace the whole tube.
So keep track of those valve caps, especially if you ride in bad conditions, all weather, or off-road. You could even give your bike a personal touch with novelty valve caps:
Some of them incorporate an LED light that not only gives your bike a cool look, but makes it more visible too. Most Montague folding bikes use schrader valves… so consider putting some of those black skulls on your ride.
As the saying goes, “you learn something new everyday”. Bless the valve caps!