Valve Caps

[SnappyPix]

Does anyone know if leaving the valve caps on inner tubes increases the likelihood of damaged valves?

I seem to be experiencing a bout of flats caused by problems with the valves, rather than p*nctures.
I'm using long valve presta tubes, as my wheels are quite deepset. I'm really carefully when pumping up the tyre (ie making sure the valve isn't bent when unscrewed, etc and use a track pump to inflate).
The problems seem to occur when doing a lot of hill work/steep, windy bendy descents and have heard that leaving the caps on can cause damage to the valve as it pushes against the cap.
I make sure the tyres are aligned properly in the rim, that the inner tubes aren't pinched or the valve skewed, but have now had 4 flats in the past 6 months from the same problem.
Does anyone have any ideas? It's not the base of the valve that seems to be the problem, rather the whole thing fails. And I've tried 3 different types of tube!

[Grog]

Really I do not think there will be a big impact on flats, but I don't leave the caps on the valves anyways. They seem quite useless (unless you ride in the dirt I guess?)...

So nothing to loose!

[SadieKate]

What do you mean by the whole thing fails? Where is the damage? If you put the tube under water, where do you see the leak?

I only leave caps on my mtbike tubes. Never heard of them causing damage. It's mostly an image thing with roadies.

[annie]

I leave my caps on because they are yellow and they match my bike. Vanity.

I've never found any reason to believe they caused flats.............. whenever I have a flat, it's for a defined reason. The only time I've had problems with valves has been using a BAD excuse for a frame pump. Or a bad batch of tubes from the LBS, and they exchanged them gladly. I've actually never heard of valve caps causing flats........ maybe it's an urban myth.

annie

[SnappyPix]

The valves seem to fail at the top end, rather than at the base. Once they go, I can't pump them up at all, let alone put them in water to hunt for the hole!
Perhaps it's an urban myth about the valve cap - it was on a UK cycling forum, and I usually only take things that I read here as gospel!

[singletrackmind]

Valve caps are on millions of cars, atvs, motorcycles and bikes, to name a few. They don't intrude on the airtight part of the tube and if anything protect the valve from being depressed.
Look elsewhere for your flats, find out where the puncture is using water, as has been said, and match the hole with wherever it is on the tire or rim of your bike. If you are getting multiple flats in the same place find the problem and fix it, if the holes are in varied places in the tread area and you don't like flats get a liner.
Ok, just saw that last post.....could your source for tubes have a bad batch? I'm assuming you are able to pump up the new tubes with no problem so it's prolly not your pump? Sometimes there is also problems with pumps damaging the valves when they are tugged off but that is usually at the bottom of the valve.
Good luck with your flat eliminating!

[CorsairMac]

My LBS actually gave me heck when they saw the valve caps were missing frome my presta valves - they told me the caps protect the valve stem especially on prestas which are so small and dainty - unlike me. So I leave the valve caps on, I just make sure I don't tighten them down too hard (think She-Ra Princess of Power when I tighten down things! LOL).

[SadieKate]

What kind of tubes are you using? Presta or Schrader?

If Presta, are you tightening or loosening the nut at the top end? If you are leaving it loose, any pressure (including a valve cap) will cause the air to leak. If you don't loosen, you won't be able to add air. Other things to check - the inner core: some stems have these and you just need to tighten this down. Also, are you carefully keeping the pump and the valve straight to each other? You can bend the valve or the little pin in the core if you don't push on/ pull off the pump straight. You can also bend it if you don't hold the valve while using a frame/mini pump.

To have a cap or not to have a cap, that is the question. The only time everyone seems to agree is that you need a cap on tubes that are rolled up in your seat bag. Then the valve is in contact with the tube and could wear a hole. Otherwise, whatever argement you accept. Everyone has reasons for and against.

[Yasmin]

To me it sounds like the fine end of the valve is leaking air. Others have mentioned tightening this properly or the cap may cause it to release air. Because you've tried different brands I think it must be a technique thing. Also, when you attempt to put air in are you opening it up fully? I keep the caps on to protect the delicate valves & to keep them clean.

[CorsairMac]

I did just remembered something:

There was a problem recently with Specialized Presta tubes here in my part of the US anyway where the valve stem itself wasn't being tightened at the factory. Which meant I was putting in new tubes and losing air by the next day. My LBS just took a pair of needle nose pliers and tightened down the stem and voila - the problem was solved. Might be worth looking into.

[SnappyPix]

Gals,

Thanks for all your suggestions, I really apprecaite them.
I'm using presta tubes, but am anally carefull about making sure the little valve release (the thing you unscrew at the top) is properly tightened whilst riding - and, when unscrewed, kept central whilst I pump up.
I've checked the rims to make sure nothing's ripping the tubes, and have stuck the tubes under water, but they don't reveal a leak - in fact, they won't pump up at all.
I think maybe I have gremlins in my tubes!
I'm going to investigate the pump - and will check the stem CorsairMac - my tubes are currently Specialized, which may explain something perhaps?
At the minute they seem to be ok, but worth checking out.

[DebW]

Sometimes presta valves get sticky and won't open when you try to pump up the tire. Opening the valve by hand a couple times before pumping usually helps. I had a sew up tire with this problem and couldn't wait for the tire to flat so I could get rid of that valve. It was a front tire and took about 4 years!