I thought I had purchased a beauty of a bike tire pump several months ago. An Ascent Mega-Force, it has a large barrel for efficient pumping, a pressure gage at the top so I can set and read it easily, and a dual head to fit both Schraeder and Presta valves. Schraeder valves work like the valves on automobile inner tubes, while Presta valves (also called Sclaverand valves somewhere in the world, apparently) are narrower and work through a cool mechanism that involves a thin threaded post and a small “captive nut” (no, not like John Hinkley) that screws down to pull up a fixed stopper on the other end of the post to block the hole. The air pressure of the tire itself, rather elegantly, holds the stopper in place. But when the captive nut is unscrewed to the top of the post and the whole mechanism forcibly depressed, the inner stopper is pushed down, away from the opening.
I don’t know the exact mechanism within a pump head that seals the pump around the open valve. But this pump was regularly balky and difficult to release from a Presta valve. It was on so tight, and so difficult to release, that it pulled off the captive nut from four of my Presta valves, thereby ruining beyond repair four perfectly good, new or newish, inner tubes to the tune of something like $32 worth of unusable rubber. I guess in theory I could have tried riding the bike as long as the air pressure would hold the valve shut, but that seemed a tad risky.
Much as I like the practice of changing tubes (something I am pretty good at now) this situation seemed not only frustrating but also ridiculous. So a couple of days ago I bought a less impressive pump made by a different maker. This one works, or seems to so far. It has a smaller barrel so inflating takes longer, and the gauge is at the bottom where I can’t read it so well. But it has a better head design and it doesn’t destroy my valves. The bike shop manager said he’d take the other one back, so that’s my mission tomorrow.
Nothing’s ever easy, even pumping air into bike tires. My mother called this the “natural perversity of things inanimate.” Thanks Mom. That’s such a great phrase!
©Arnold J. Bradford, 2012