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My new bike has these thin tires with a type of valve I haven't usedbefore. I searched online and found out it's called a Presta valve, and it's pretty common and popular. I'm finding it annoying and fiddly and don't know how to use it properly. I have a floor pump, and I know the valves and pump are fine, because the guy in the shop had no trouble using the same one. But after reading online and watching YouTube videos I still can't figure out how to do it properly!

Here's what I'm trying:

  • Rotate wheel so that the pump can comfortably reach the valve (guides online say the valve should be at 12 o'clock position, but I can't do that because the hose on the pump isn't long enough)
  • Remove valve cap, unscrew thingy in valve, and tap it a little - a jet of air shoots out. OK.
  • Push pump onto valve. This is where I get into trouble...

I can't seem to get the attachment onto the valve in the right way. I'm pushing it on with the elbow lever thingy down, and then pulling the lever up as you can see in the pictures, to make the attachment grip onto the valve.

Now, either it flops around loose and leaks air out the sides (when I push it on gently), or sometimes it goes on but then the tire doesn't seem to inflate any, the pump just gets stiff really quickly as if the valve was blocked - then I remove the attachment and it goes pffffft like all the pressure was just backed up in the hose and not actually going into the tire.

I was able to pump up the tire eventually, but it took me about an hour of stuffing around and my "project manager" got angry, because I was supposed to be in the kitchen making her a salad, not mucking around in the garage.

The time I got it on properly I had to deflate the tire completely, and even then it was difficult because with the tire completely deflated the stem of the valve just pushed into the rim. Surely this is not normal? What's the trick of attaching the darned thing?

Also, how can I just check the pressure? When I attach the thing I expect the guage to jump up and show me what pressure it's at, but it just stays at 0. The tires say on the side to inflate to 110 psi (7.5 atm), but my pump only goes up to 100.

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I always put the valve at 6 o'clock (closest to the floor) when filling. That way when you push the pump head onto the valve, the bike doesn't go anywhere. With my pump, I have to get the valve quite deep into the head and it's difficult to do this in any position other than having the valve at the floor. –  Kibbee Dec 3 '12 at 17:58
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Looking at the picture, it seems you may not have enough of the stem protruding to actually connect it properly to the pump head. I have similar rims on one of my bikes, and I ended up getting a valve adapter as @Zippy mentioned below instead of buying longer stems, as they cost more than the shorter stems, and the adapters are quite cheap anyway (75 cents at my local bike store). –  Kibbee Dec 4 '12 at 1:35
    
@kibbee - I like the stem high, so I don't need to bend over as far. But I don't have aero rims. –  Daniel R Hicks Dec 4 '12 at 2:33
    
Presta valves are typically used in cases where a higher tire pressure is required - the pump you are using may not be able to handle pumping a tire up to 110 PSI. (or the guage may simply not show the pressure, in which case you may need to be careful of a blowout.) –  tofarr Dec 5 '12 at 11:37
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5 Answers

up vote 8 down vote accepted

Those valve stems are too short for those deep deep rims you've got on there. You can tell just from the photos that the valve stem isn't sticking out far enough from the rim for the pump to fit all the way on it. Hence, it's not contacting the valve enough for you to inflate your tires.

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You're absolutely right. There should also be a jam nut to keep that stem from wiggling around when you try to get the pump head seated. –  WTHarper Dec 4 '12 at 2:10
    
Yep, I think you've got it. Who supplied those wheels with too-short stems?? (I've had the problem that it's hard to find shorter stems for my regular box rims anymore -- surprised that this situation would ever occur.) –  Daniel R Hicks Dec 4 '12 at 2:32
    
I've done this before by accident - you need to get tube with a 60 mm valve instead of a 42 mm value –  tofarr Dec 5 '12 at 11:33
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Inside the Presta pump head there will be a peg behind a rubber washer, which depresses the valve on the stem which is engaged when you move the lever into the elevated position. At the same time, typically a set of jaws will clamp onto the body of the stem holding it in place. It sounds very much as if your pump isn't able to activate the valve sufficiently to break the seal, and therefore when you pump, the air is backing up against the rubber washer rather than inflating the tyre.

As mentioned above, this could be an artifact of the exposed stem not being long enough and you should look to: use either a chuck which doesn't require as much stem to be exposed; to replace the inner tube with one with a longer valve; or use a valve extender (that leaves the existing core intact), or if the tube has a replaceable core to screw in a valve extender (like those available from Continental).

Sometimes, I find it useful when pumps aren't functioning as I'd expect them to, is to use an inner tube with a known working valve without it being installed in a tyre. This will remove the potential for insufficient stem being exposed to be a limiting factor and permit the pump to be exercised to ensure it is functioning correctly.

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The pump appears to have a valve which is supposed to switch automatically between Presta and Schrader as needed. In my experience, these valve don't always work. I have a similar pump where the valve has become stuck, and I can only use it for inflating Schrader valves now.

If this is at the root of your problem as well, among many alternatives, you can 1) buy a new pump, or 2) get a Presta-->Schrader adapter.

My guess would be that if you operate the pump off the bicycle tire, air should come out the Schrader valve side. This will show you in which mode the valve is operating.

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I've got a pump that switches quite well, but it's a good quality "Joe Blow" unit. The OP's pump appears to have a chuck with two holes in it, one for Presta and one for Schraeder, so it doesn't really need to switch. –  Daniel R Hicks Dec 4 '12 at 2:36
    
Yes it has two holes like that –  wim Dec 4 '12 at 12:11
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"Remove valve cap, unscrew thingy in valve, and tap it a little - a jet of air shoots out. OK."

You've got that right. If you have the proper pump, and the chuck is working properly, then simply pushing the chuck on and flipping the lever should do it.

Normally, when you press the chuck on far enough a little button in the middle of the chuck will press the "thingy" down to let air out and let you read the pressure.

It may be that your chuck is poorly designed (or not really "stem agnostic") and you'd do better with a screw-on adapter. (And some chuck designs require changing out the innards to do Presta valves.)

(It really isn't that difficult and fussy with the right pump and the right technique.)

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You need a special Presta valve suited to the tire pump or an adapter to convert your bike tire's valve temporarily to a Schrader tire valve, so you can use a standard tire pump. After filling, you remove the adapter till the next time.

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Welcome to Bicycles SE. This answer would be more complete with links and/or pictures to the type of pump and adapter that you're talking about. Please consider adding them. –  jimirings Aug 6 '13 at 12:22
    
A presta->schrader adapter was already mentioned in Zippy's answer, and the original user already has a pump compatible with presta valves. –  Tim B Aug 7 '13 at 17:19
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