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?

No. But I have metal valve caps. They are red, so they are the fastest.

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.

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?!

It was bent by the pump head.

Just replace the core with a new one.

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.

And if you use a hand pump on the road. Less chance of tearing the valve off the tube, which I have seen done.

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

Sorry, but my stem extensions are not threaded.

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.

My tubeless presta covers are metal and also a core remover.

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.

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.

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.

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.

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.

Don't do that. Just take care when using your pump. Presta valves without caps look way sexier than Schrader valves without caps.

Plus the caps add additional rotating weight to the wheel

I use metal caps myself, but my cycling son doesn't use caps. He says he doesn't want to carry the extra weight.

If you want "sexy" just ride behind me

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

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.)