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Archive for November 23rd, 2011

Presta Valve: Proper Pump Attachment Thereto

All our bikes have Presta valves, which seem better suited for bike rims than the larger and more common automotive Schraeder valves:

Presta valve stem

Presta valve stem

For all these years, I’d been attaching the pump head so the obvious sealing ring near the nozzle opening lined up with the flat section adjacent to the valve core stem. The pump head never seemed stable on the stem, often leaked, and generally had a precarious hold:

Incorrect Presta pump head attachment

Incorrect Presta pump head attachment

Come to find out, more by accident than intention, that the correct way to attach the pump head involves ramming it all the way down onto the stem so that it can seal along the entire length of the threads. That’s nice and secure, doesn’t leak, and even looks like it should work perfectly:

Correct Presta pump head attachment

Correct Presta pump head attachment

I’d feel even more like a doof if I hadn’t learned to do it wrong by watching somebody else back in the day or if I haven’t observed many other people making exactly the same mistake. I think the fact that the short nozzles on the old-school Zéfal pumps I swore by back in my wedgie-bike days never got a good grip on Presta stems got me off to a bad start, but … dang do I feel stupid.

FWIW, the little tab sticking out under the latch handle makes up for a bit of slop in the valve head. When I got the pump, the Schraeder nozzle didn’t seal very well, either, and taking up a few mils of slack helped immeasurably. We don’t need that nozzle very often, but our bicycle touring guests frequently do; they know that they can top off a Schraeder-valved tube at any gas station or with any pump anywhere around the world.

[Update: I hate it when I misspell a word in the title…]

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