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I've now had two floor pumps 'break' in use, a Beto and a Vandorm, the latter on the first use. Both are dual Presta-Schrader. Both 'broke' while attempting to inflate a Vavert 700X28/35C Presta inner tube in a Continental Ride Tour 700x28C tyre. The tubes are on the big side for the tyres, but this hasn't been a problem in years of use. The maximum recommended pressure on the tyres is 70psi, and I now realise that when the Vandorm pump broke I was applying around 100psi of pressure. (I'm not very bike savvy.)

Now the situation with both pumps is as follows.

  1. If I raise and depress the plunger with both nozzles uncovered then air flows freely out of both nozzles.
  2. If I attach the Presta nozzle to an inner tube and raise and depress the plunger then air flows out only through the Schrader nozzle.
  3. If I cover one nozzle with a finger and raise and depress the plunger then no air flows out of the uncovered nozzle, but I can feel air pressure on the finger over the covered nozzle. This seems odd, because it seems to be the opposite of (2).

All of this seems to be independent of the position of the lever.

Does anyone know what might have happened, and if it's fixable?

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    If it was me, considering the Vandorm broke on first use. I'd be taking it straight back to where I got it from without any attempted fix. I'm assuming you've been using the Beto for some time so assume you know how to use it and whatever happened there could be just plain wear and tear
    – Hursey
    Mar 21 at 2:34
  • @Hursey Yeah, the Beto's a couple of years old, and I could return the Vandorm. But since they broke in exactly the same way I'm wary of getting a third pump and having the same thing happen again because of something I'm doing wrong.
    – mjc
    Mar 21 at 2:36

2 Answers 2

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You say that you feel pressure in the side that's blocked when you cover it with your finger. In my experience these pumps that automatically switch where the pressure is being directed need a certain amount of back pressure in order to work properly.

If you connect the pump to a partially inflated tyre, does it select the correct fitting to supply air to?

I have a pump like this (and the previous one was the same), and while it's fine for adding pressure to a tyre, it's always a bit of a pain when pumping up a completely deflated tube.

The trick to making it work is to squeeze the tube against the back of the valve, creating a blockage of the air (with the pump attached to the valve). Just like when you put your finger over one of the holes, this should be enough to switch pressure to the correct side.

Sometimes, if you've got a very flat tube in a larger volume tyre, or the pump's capacity isn't that large, you may have to do it more than once, but as soon as you have a modicum of pressure in your tyre it should work.

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    This. In my experience it sometimes also helps to “switch” the pump to the correct hole with your finger first, then attach it to the (completely deflated) tube.
    – Michael
    Mar 21 at 8:18
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    Your description confirms my thinking that the design is rather dumb, introducing an unnecessary extra failure mode
    – Chris H
    Mar 21 at 9:01
  • This seems to have worked. Thanks.
    – mjc
    Mar 21 at 17:00
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Heads are replaceable, and if just the head has failed you can get a better one. Pump hoses aren't universal, but are usually close enough in size to be able to swap heads

I much prefer a non-automatic head - just choose the right hole for the right valve, put the head on the valve and lift the lever. My floor pump has one very similar to this Topeak Jow Blow which is easily available (probably cheaper than where I've linked but the first hit happened to be a shop I've bought from online).

The head is the most likely part to fail on a pump. Piston seals can be regreased and even replaced (I used a generic O-ring in my Road Morph) and gauges can fail but normally only if they get wet. So I assume the failure can be pinned down to the head

In your position, I'd consider returning the new pump, and repairing the old with a new head, costing about half what a new pump costs.

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