tchazzard

Hi; My LBS only carries Kendra tubes. I have found that the presta valve sticks on almost all of the Kendra tubes I have used. It takes a few tries before I can get air into the tire. Has anyone else seen this?

I just ordered some Novara tubes from REI to see if these work any better.

Thanks.

pokey

It really makes no difference.'Burp' the valve before you put the pump head on.

tchazzard

I do burp the valve...but these Kendras are more finicky than any other presta tube I have had.

RonH

I've used Kenda tubes (not Kendra) for a few years and haven't had any problems.
Are you opening (unscrewing) the stem before you try to pump up the tube (tire)?

tchazzard

Yes I am unscrewing...I had good luck with these tubes in the past...but seems to be the last 2 or 3...I have been using presta valve tubes for a lot of years and have never had them misbehave like this in the past.

BILLB58

replaced tubes and tires last month, and all of a sudden, having a similar problem, must be the batch of tubes as am having the same problem with both tubes......sometimes have to get to 140lbs of pressure before valve opens...I try to keep mine at 100 lbs psi, so once valve opens, tire is usually at 90 +/-, so I add 10lbs.....no big deal doing this at home with a floor pump, but if I have a roadside issue, getting to 140lb psi with a hand emergency pump will be a challenge...

maybe I should use a little silicon spray on valve?

GeoLes

I assume that "burping" means depressing the valve head to get everything moving....

I have had the same issue on occasion. Sometimes the valve gets stuck. I don't know which tubes I have. (I usually get what's on sale), but by unscrewing the stem valve and depressing usually allows me to pump it up.

What sort of pump do you have. There is a possibiltity that it may be your pump valve head. I use a floor pump 90% of the time.

kenhill3

On a related note, here is some info I discovered about defective presta valves:

https://www.machinehead-software.co.u...ta_valves.html

jim p

For what it is worth. I have one valve which if pushed open by .002" inch it can be filled but if pushed open by .004" it will again seal and can not be filled. It works fine if I just unscrew the stem and then put the compressor on and let the air force itself by the valve. None of my other valves give me any grief.

GeoLes

You use a compressor? I have never used one on a bike tube (except that one time I exploded a tire when I was a kid). I would imagine that may have something to do with your problem. I would invest in a good floor pump; preferrably one with a built in pressure gauge. You may find that your problem goes away (unless the valve quality does in fact make a difference, that is.)

Rowan

I find it can happen on any brand of presta-valved tube I use, and more so if they have been dormant for a long time. It can be disconcerting to apply the head of the pump (floor or frame) and to find suddenly that high-pressure strokes are required. It really has only needed the stem of the valve to be pushed in, twisted a bit and pulled up and down to get it to perform properly.

However, if your valves are defective... ?

jim p

My compressor cuts off at 120 psi so I just let it pump up its tank and cut off. Then I connect it to my road bike tire for about 15 seconds and the tire is at max pressure. Now if I am filling a mtn bike tire for 55 psi, I have to be careful and make short fills and readings to make sure that I don't over pressurize the tire. I have a pressure regulator which I should install on the output line of the compressor and then I could just dial up the pressure that I want and connect it to the tire and come back later and disconnect it but that would be too easy.

So far I have been successful with my filling technique. I have also noticed that the bike shop likes to use a compressor but they do have a floor pump for customers to use.

turtle77

I've also begun to have the same problem in, say, the last two years. Actually, it's not really a problem so much as it is an annoyance, but yeah, it's something I've noticed, and for whatever reason it wasn't happening before. BTW I use Bontrager tubes, so it doesn't seem to be brand specific.

soma2x

I use the Novara tubes too. I think they are made by kenda and I know their valves stick. I tap the valves to let some air out first then start pumping. Usually the pressure builds up in the hose so that my guage reads over 100 and then the valve pops audibly. At that point the pressure guage drops to whatever the actual pressure in the tire is (usually 80 something before I top them off) and you can pump your tires up. I don't know that any other valve will work any better but I would like to try Schwalbe's which I hear don't lose pressure for a long time.

Falchoon

Same problem I have too and I also don't know what brand of tube because I usually just buy whatever is cheap. I have a Tioga brand track pump. I have had the problem with 3 or 4 different brand tubes lately, never previously. I suspect there are only a handful of actual tube manufacturers and they are just resold/rebranded to other resellers so they are actually all the same brand.

That's exactly what happens to me. Sometimes if you give the pump head a bit of a wiggle it will come good too, sometimes not though.

I'll have to stop buying cheap tubes I guess.

While on the subject of tube issues, does anyone have a preference for the threaded valve stem (as shown in pic in machinehead-software link) of the smooth stem? I prefer the threaded stem so I can put the lockring around the bottom to help the valve stick out of the rim while changing the the tube. A guy at LBS said smooth ones are better because the threaded ones damage the rubber seal in the pump head.

Falchoon

I experimented by putting a drop of chain lube on the valve and the problem now seems to be solved!

soma5

I have had the same problem with Specialized tubes. I don't seem to have the problem at all with either Continental or Michelin tubes. I don't know about chain lube in the presta valve, though. I recall that there used to be warnings about petroleum products getting onto and reacting with the rubber of the tubes.

-soma5

LEATHERNECK

These tubes have a smooth valve stem, which may solve your problem. https://www.wekeepyoucycling.com/en/c-2-tubes.aspx