Presta valve cores - Quality differences?
 

I just had two out of four brand new Continental Race 28 tubes come with bad presta valves right out of the box. Hard to believe that quality control has gone down so much, especially with Conti tubes. So now I have a couple of tubes without valve cores, and apparently the quality is crap nowadays so I'm going to need more spares.

I can buy 10 or 20 packs of them for cheap and some even come with an extra removal tool, but I'm assuming they're all cheap Chinese junk. Is anyone aware of any particular brand that is better than others? I don't mind paying for higher quality, if they're more reliable and hold air.

What happened to the valve cores and are you 100% sure without any doubt it wasn't your pump and you used a valve core tool to make sure things were tight? I have seen a lot of pumps help remove valve cores that are loose and plenty of different brands that have loose cores or have cores that have loosened up over time. I just use my trusty little valve core tool from Park or Stans makes a good one and just tighten it up. Many of the twist on pumps can cause issues like that and just checking with that tool before and after will keep things relatively problem free. I haven't had that issue with Conti tubes but I haven't bought them in a little while since I usually buy a bunch and stockpile for a bit but I haven't had many flats in the past few years,

...I had the exact same experience with an order of 8 Conti tubes in bulk (not individually packaged) from a vendor on Amazon. I've ordered before from the same source without problems, but the first four had bad valve cores, so I sent the second four back for a refund. the ones I had already mounted in tires, it was easier to order whatever Presta valves I could find on Amazon in a package of 20, and they worked fine. I'd be surprised if there were anyone making these outside of Asia at this point.

It sounds like another potential counterfeit on Amazon. Any name brand bike part on Amazon I am suspicious of.

I bought five Specialized tubes from an online bicycle shop and were in bulk packaging. Three of the five had bad presta valves. They leaked until you screwed them down.

Recently I bought a few Michelin tubes and no problems with the valves. I also like Michelins because the valve stems are smooth (unthreaded) making it easier on my pump head.

Aren't they supposed to be screwed down?

I can't believe anyone would expect to leave the cap of the core just loose and about.

Lesson learned the hard way. Test all your spare tubes before a long ride.

The tubes came individually boxed and if they're counterfeit, they're damn good ones. Not just the box, but the printing on the tubes itself is identical to other Conti tubes that I have.

The valves were removed and reinstalled, and were nice and tight. The problem was that once the pump head was removed, the self-sealing mechanism did not work and the air just leaked out, much faster than I could close the valve. A good valve under pressure might show some slow bubbling when held in a cup of water before it's screwed down, but these just wouldn't seal. I literally could not close the valve fast enough to prevent significant air loss. Close inspection under 10x magnification reveals that the shafts don't sit straight and the washer is cockeyed. I've had far fewer problems with valves in the past and have been using my backstock for a few years now. It seems that there has been a decline in quality, and apparently I'm not the only one. Continental may individually test their tubes, but it's clear they don't test each valve that they install.

I kept this project on track by just cannibalizing valves from other spare tubes, but now I need replacements. My question is whether I should just order the 10 or 20 pack from Amazon (there are several vendors and I assume they're all the same) or if there are better valves that I can pay a little more for and get better quality.

I expect there is someplace in China where you send some original product packaging and they analyze the paper ink etc and make exact copies. It has gotten a lot better recently .. look up some threads here on Shimano chain counterfeits where there are pictures of the counterfeit ones. I would look at the seams on the tubes, while they can print the same thing on the tube they are not going to use the same machine to make the tubes so the seams and the area around the stem should be different.

Apparently, you don't understand how a valve is supposed to work.

Even though it's designed to be screwed down, it shouldn't leak at all - screwed down or not.

I know exactly how they work, but thanks for your concern and mistakenly thinking I did not.

If you understand how a valve is supposed to work, then what is the relevance of this post:

My problem with the bad valves was once the pump head was removed, air was leaking at a pretty good rate. By the time I screwed the valve close, I felt enough air was released to render the tire under-inflated. In my 30+ years of using presta valves, I've never had this happen, and I chalked the leaking valves up to poor manufacturing. I guess statistically, it's bound to happen.

On a properly operating presta valve, the differential pressure inside the tube versus the atmospheric air pressure should seal the valve completely, without screwing down the valve. I just about always screw the valve shut, But there've been a few times when I did not secure the screw and only discovered this after the ride, and never noticed air loss.

Every season I install at least a hundred tubes, I've used presta tubes of all makes and manufacturers, from cheap to premium, and they all equally "leak" upon pump removal.

Some none, some little, some more than others, but they don't qualify as a "defect".

I'm not going to return half my stock back to vendors because I didn't get the perfect tube.

Why do they leak? My guess is the talc inside the tubes. Maybe they use more today than yesteryear. I just never bothered with it. I suppose I could remove the valve and clean it, but time is money when flipping bikes.

You got lucky, but to expect that a presta tube must perform without the cap closed is negligence.

To the original question, I haven't noticed any significant differences in valve cores, including bulk purchase from Amazon.

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...FWIW, I had the opposite problem. The valves on my tubes required a great deal of over-pressuring at the pump in order to inflate them. Once inflated it was either difficult or impossible to let any air out at the valve by using the Presta thingie that screws in and out (up and down ?). To deflate them, I had to unscrew the entire guts of the valve core mechanism. And if these were counterfeit copies, they were damn good ones. The rest of the tube looked like every other Race 28 Continental I've ever bought and used.

Anyway, those valve mechs on Amazon I linked in my first post work fine.

They are loose between when you take the pump head off, and until you screw them down several seconds later. A presta valve is designed to hold air during that time, even if they aren't tightened down. That's the problem - these don't.

You must not have any wheels with presta valves.

That's exactly what happened with these - too much leakage before I could screw the cap down. I also haven't had this problem in all my years of using presta valves.

And how so?

I bought Schwalbe tubes and they came with awful Presta cores, one of which did hold air right from the beginning. In the particular tube size/Presta combination, Schwalbe is the only practical option. I got these cores from AliExpress and they are of good quality. The problem with Ali is that it takes a month+ for the order to arrive. However, maybe the photos can serve as a guidance.

Thanks for the feedback everyone. I just bought a pack of 20 from Amazon. I'm not hearing that there is anything substantially or provably better.

Update. I bought two packs of these from Amazon. The two that I needed replacements for (with the Continental tubes) worked fine. I also examined them under a high-power loupe and they seem much better quality. The washers are thicker and more uniform, the valve seats are straight, the materials are better, and they just look like they are manufactured to higher tolerances. Even the knurling on the knobs are finer and more uniform.

It's very reasonable to assume that even though high-end tube makers like Conti or Schwalbe do produce good tubes and perform a thorough QA on them, they then go ahead and install valves purchased from the lowest bidder.

Presta Valve Core - 10 Pack

I recommend shooting Conti and email including a photo of the bad valve or valves. Maybe even a link to this thread as bad publicity is not good for business. It may be something they would be concerned enough about to do something or can tell if it's counterfeit or not.

It's not just the valve cores are having quality issues it's the wall thickness is not uniform and cause tubes to fail.
I had two recently purchased Conti 25 tubes explode while inflation testing like I have for over 20 yrs with no failures until now.
I am done with Conti's. Also wear ear/eye protection while testing or you may have a loss of hearing !

Thanks for the update. I just ordered that same 10 pack yesterday. Couple valves on my tubeless valve stem were not functioning well so I had to grab some new ones from my stash that worked better and replenish my stock.