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After my $20 floor pump from the hardware store gave out. I bought a rather more expensive one rated to 160 PSI. The pump has a metal nozzle on it, with a Schrader opening on one end and a Presta opening on the other.

I find closing the Presta side of the nozzle requires an extremely large amount of force. It seems like I get a much tighter seal with it, and that I can go to higher pressures as a result. However, because it requires so much force to close I have ended up bending the valve stem every time I use it. Ultimately I've gone back to using the Schrader adaptor I had for the old pump, along with the Schrader side of the nozzle, which is much easier to close.

Is there a trick to closing a purpose-designed Presta nozzle? Is my pump defective somehow?

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2 Answers 2

up vote 4 down vote accepted

I've never had this problem. It would take considerable force to bend the stem.

First be sure you have the nut on the Presta stem, and that it is screwed down firmly against the rim (though it shouldn't be wrenched tight). This will keep the stem from wobbling around in the rim hole, and makes the whole job easier.

Then make sure that the wheel is rotated around to where the stem is easy to reach, and the pump is pre-positioned so you won't have to fight the hose to get the chuck on.

With most chucks you press the chuck on, the raise the lever on the chuck, but a few you raise the lever first, install the chuck, then flip the lever down. Be sure which style you have.

Prepare the chuck for installation, press it on squarely, then, while holding the chuck with one hand raise/lower the lever with the other.

Note that on some chucks there is an adjustable collar on the end of the chuck which you can screw in for a tighter fit, out for a less tight fit. You want the collar (if present) adjusted to allow the chuck to slide on with only mild resistance, then grip firmly when the lever is raised/lowered.

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Agreed - I have had 8 or 9 presta pumps, and while some take a couple of fingers to close, none have been difficult. –  Rory Alsop Jul 28 '13 at 19:12

You are almost certainly doing something wrong, so why not simply pop back to the shop and get them to show you how they use the pump that they sold you?

Bending the valve stem is virtually impossible - if you are bending anything it is perhaps the valve body.

Take care to ensure that after you release the thumb-lever lock (you ARE releasing it, aren't you?) that you remove the head of the pump without wiggling it, as such an action is sure to bend the valve body.

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