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Presta valve caps

Old 12-29-21, 12:47 PM
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LarrySellerz
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Presta valve caps

You know those plastic valve caps that everyone throws away? Well my presta valve is leaking and I have to throw the tube away. It looks kind of bent. Think I should have kept the valve cap? Has anyone else had a presta valve leak, and think its because you didn't keep the protector on it?
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Old 12-29-21, 12:49 PM
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No. But I have metal valve caps. They are red, so they are the fastest.
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Old 12-29-21, 01:00 PM
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Some presta valves can be unscrewed so check the tightness. You can also use a pair of plyers to straighten the presta valve stem. I have florescent green valve caps.
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Old 12-29-21, 01:12 PM
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I always use the plastic caps on both presta and Schrader. I've always felt they are another layer of protection for keeping dirt out that might cause a valve to leak. Maybe it only happens once every other blue moon but once anytime is probably going to be the worst time for it to happen.

I don't look at other peoples wheels to see what they do for their valve stems. I don't know why they should be looking at mine and care whether I do or don't.

I even use the little nut that goes on the presta stem too. I guess I'm a maverick?!
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Old 12-29-21, 01:19 PM
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It was bent by the pump head.

Just replace the core with a new one.
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Old 12-29-21, 01:28 PM
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I don't use the cap because it's inconvenient to unscrew them every time I inflate the tires, and I rarely get a bent valve, but it does happen. As mentioned above, you can just swap the core out. You could even start collecting cores from tubes you're about to throw away, giving you a stash of spares.

Originally Posted by Iride01 View Post
I even use the little nut that goes on the presta stem too. I guess I'm a maverick?!
These are very useful for when the tube goes completely flat and the pump head tries to push the whole valve inside the rim before engaging fully.
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Old 12-29-21, 01:38 PM
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Originally Posted by urbanknight View Post

These are very useful for when the tube goes completely flat and the pump head tries to push the whole valve inside the rim before engaging fully.
And if you use a hand pump on the road. Less chance of tearing the valve off the tube, which I have seen done.
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Old 12-29-21, 01:59 PM
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Originally Posted by LarrySellerz View Post
Has anyone else had a presta valve leak, and think its because you didn't keep the protector on it?
Nope. The plastic cap won't keep air in the tube; they don't seal tight enough, and if the valve is open, the cap will just push down on it and make it leak faster.

The only use I have for a presta cap is as an emergency shraeder adapter. Cut off the tip, turn it upside down, and screw it on. You can then use a shraeder pump or gas station compressor.






https://www.purecycles.com/blogs/bic...hrader-adapter

Last edited by Rolla; 12-29-21 at 02:03 PM.
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Old 12-29-21, 04:10 PM
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Originally Posted by Iride01 View Post
I even use the little nut that goes on the presta stem too. I guess I'm a maverick?!
Sorry, but my stem extensions are not threaded.
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Old 12-29-21, 04:36 PM
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I have metal valve caps in blue to match the decals on the bike.

If you have to have a fault, vanity isn't the worst choice.
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Old 12-29-21, 04:54 PM
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My tubeless presta covers are metal and also a core remover.
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Old 12-29-21, 04:59 PM
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Originally Posted by GlennR View Post
It was bent by the pump head.
.
Correct answer.

I don't see how the valve could be bent by anything else, since that would probably impact the spokes, too.

Valve caps are useless.
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Old 12-29-21, 05:38 PM
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Yeah, bent presta valves are user-induced, usually by being rough when putting the pump chuck on or taking it off. Presta valve caps are strictly for style.


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Old 12-29-21, 06:00 PM
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I use the caps like I give a damn until I lose one or break one, Then I remove it from the other wheel and ride like I don't give a damn.
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Old 12-29-21, 06:27 PM
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I was sure Sheldon Brown argued they were useless once the tube was unfurled, but I can no longer find that quote. Lacking Sheldon's backing, I may have to reconsider my position as a Presta valve cap denier.

With a sharp instrument you can modify a (plastic) Presta cap to be a functional Schrader adapter, thus fill your fancy bike tire at a gas station. So I guess that's an argument to carry a sharp knife and mount your Presta caps.
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Old 12-29-21, 06:58 PM
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Originally Posted by downtube42 View Post
I was sure Sheldon Brown argued they were useless once the tube was unfurled, but I can no longer find that quote. Lacking Sheldon's backing, I may have to reconsider my position as a Presta valve cap denier.

With a sharp instrument you can modify a (plastic) Presta cap to be a functional Schrader adapter, thus fill your fancy bike tire at a gas station. So I guess that's an argument to carry a sharp knife and mount your Presta caps.
You're not crazy; I remember reading Sheldon (or maybe Jobst Brandt) saying that the only purpose of the cap was to keep from poking a hole in the tube while it was rolled up.

I no longer throw away valve caps, though -- I patched up a bunch of old tubes a year or two ago and wasn't able to roll them up properly since I was short on caps.
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Old 12-29-21, 07:21 PM
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So it was damaged by the pump and the cap didn't matter.. got it, makes sense. I wish I could just use shrader but I don't think my wheels allow it.
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Old 12-29-21, 07:46 PM
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Originally Posted by LarrySellerz View Post
So it was damaged by the pump and the cap didn't matter.. got it, makes sense. I wish I could just use shrader but I don't think my wheels allow it.
Drill the valve hole larger... if you must.
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Old 12-29-21, 07:54 PM
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Originally Posted by LarrySellerz View Post
So it was damaged by the pump and the cap didn't matter.. got it, makes sense. I wish I could just use shrader but I don't think my wheels allow it.
Don't do that. Just take care when using your pump. Presta valves without caps look way sexier than Schrader valves without caps.
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Old 12-29-21, 08:02 PM
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Originally Posted by urbanknight View Post
I don't use the cap because it's inconvenient to unscrew them every time I inflate the tires, and I rarely get a bent valve, but it does happen. As mentioned above, you can just swap the core out. You could even start collecting cores from tubes you're about to throw away, giving you a stash of spares.


These are very useful for when the tube goes completely flat and the pump head tries to push the whole valve inside the rim before engaging fully.
Plus the caps add additional rotating weight to the wheel
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Old 12-29-21, 08:04 PM
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I use metal caps myself, but my cycling son doesn't use caps. He says he doesn't want to carry the extra weight.
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Old 12-29-21, 08:13 PM
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Originally Posted by Chuck M View Post
Presta valves without caps look way sexier than Schrader valves without caps.
If you want "sexy" just ride behind me
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Old 12-29-21, 08:21 PM
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Originally Posted by TomM View Post
Plus the caps add additional rotating weight to the wheel
Too bad I have more added rotating weight in my little toe.
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Old 12-29-21, 08:33 PM
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Originally Posted by urbanknight View Post
Too bad I have more added rotating weight in my little toe.
I don’t have a good use for my little toes either.

John
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Old 12-29-21, 09:18 PM
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Originally Posted by ThermionicScott View Post
You're not crazy; I remember reading Sheldon (or maybe Jobst Brandt) saying that the only purpose of the cap was to keep from poking a hole in the tube while it was rolled up.

I no longer throw away valve caps, though -- I patched up a bunch of old tubes a year or two ago and wasn't able to roll them up properly since I was short on caps.
I fold my tubes from opposite the valve. Valve is last and lays on the rolled tube. Held in place by the elastic. Haven't punctured a tube yet in many years. (I sometimes have to roll twice to get the valve to lie on the tube, not be at the folds.)
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