Idiot/novice question -- please help me help myself
 

I broke my (presta) valve this morning inflating my tires for the second time in one week. I am using a Topeak Joe Blow pump and must be wiggling it too much when removing the pump? Does this happen to anyone else? How can I *not* do this? Please help me. Thanks :)

Danni

Do you have threaded presta valves? I find that the ones that are threaded (and I use the nut) are less likely to tear at the valve/tire spot.

Not a dumb question at all.

By any chance, did you tighten up the nut on the presta valve stem? This is a one-way trip to tube disaster.

It should be loose, and many just throw it away.

This is my guess as to the cause of your problem.

...and welcome to Bike Forums!

I think they are threaded. :eek:

Thanks for the welcome. I think I loosened it first but it's possible that I didn't loosen it enough, or forgot. It was evident that I didn't have everything properly ready because it was not letting me inflate. As I was removing the pump to re-attempt I broke the valve stem. So maybe this was the problem.

There is the little nut on the centre of the valve stem that you must undo to let air in the tube. The nut eubi was talking about is the one at the base of the valve that clamps against the rim - this should not be screwed tight. To avoid bending the valve centre pin, you must pull the pump chuck straight off the valve without wriggling it around.

OK. There's the little valve at the end -- I know that one must be loose to fill the tube and then you screw it back afterwards.

There's another nut? There was another one that I just put near the rim. I wasn't sure what the purpose of that one was other than to keep the valve from being pushed up into the rim.

It sounds like my main problem might be wriggling the pump chuck (is that what it's called?) rather than pulling it straight off.

yes. this happens when people do it hurriedly, to avoid losing air from the tube in the process. However, I have it on decent authority that any air lost in this operation is only from the pump's hose, not the tube.

I don't know about the Topeak pump, but on some pumps you have some ability to adjust the tightness of the rubber cyclinder that the valve stem is inserted into....I don't just mean when you flip the lever to secure the pump to the stem, but even when the lever is down. I presume the pump head has a kind of "bottle cap" cover that screws on and holds the rubber cylinder in the pump head. Maybe if you loosen that bottle cap slightly, it will relax that rubber so it won't grip the stem so tightly as you're trying to remove the pump from the stem.

I bent the little stem inside the valve by letting a 4yr old girl "help" pump my tire to the point that it wouldn't lock shut, so I'd imagine they could break pretty easy if you wrench the pump off. I now take it off by putting two fingers around the valve and pulling the pump off to avoid this experience again.

Where did you break the valve stem? At the base? At the valve?

If it is breaking at the base of the stem, your problem may be that you are running presta in schraeder holes (too big). The tube sneaks out and eventually gets pinched. I lost a lot of tubes before I figured that out. You can fix this problem by installing valve stem adapters http://wheelsmfg.com/products.php?ca...restastemsaver .

Yes, that is exactly its purpose, but it should not be tight against the rim, just near it so that it gives something to push against when putting the pump on.

Ok, I'm curious... what is the reasoning behind why not to tighten the nuts at the base? I've always just put then hand-tight, seems to be ok.

Had the same problem with the same pump a few years ago; be less forceful and use a different brand of tubes

the skinny screw part is what is breaking off.

If you are using the threaded type, put the nut back on so that it touches the rim loosely as stated before. Then place your hand around the tire so the valve stem is in between your index and middle finger. The nut will provide some more surface area for you to grab. Tighten your hand up to offset the force being applied by the removal of the pump in the opposite direction. Try not to wiggle the valve stem too much, and pull straight off.

I actually prefer the smooth valve stems. My pump comes off of those much more easily.

Too much wiggling when trying to remove the pump head (chuck).

Two things here. One is try not to push teh pump head down too much. The other is once you have flipped the lever back on the pump head to release the valve then turn your wiggling motion to a gentle twisting. Be careful though, if the valve looks like it's twisting as well then stop.

Other hint is hold the wheel so that the palm is on the tire and you have a finger either side of the valve. Hold teh pump head with the other hand and pull striaght. If possible use your body weight.