# Keep getting leaks at valve stem. Fixes?



## CHRISTO (Mar 19, 2004)

I keep getting leaks at my valve stem/tire junction. I suspect a lot of the problem is the threaded valve stems. I've got to work it out of the pump fitting whenever I air up the tires and it weakens the stem. I'm going to threadless to fix that. Any other suggestions to help? Thanks


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## Creakyknees (Sep 21, 2003)

Check the inside of the valve hole to make sure there are no sharp edges / burrs. Take a small rat-tail file or just some rolled up sandpaper or maybe an emery board and clean it up. Make sure the valve hole in your rim tape is aligned to protect the tube from the valve hole edges. 

Be careful when attaching / removing the pump head. When the tire's flat and I'm first inflating, I grab thumb n forefinger across the fat body of the tire and pinch tightly to hold the tube and valve in place while securing the pump head. Then pump a few strokes to get a bit of shape, and double check everything's lined up right. 

When removing, use 2 hands on the pumphead - one to hold it steady, the other to release the lock lever, then both to pull it straight off the valvestem.


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## Einstruzende (Jun 1, 2004)

If you use the "nut" on threaded stems, don't.


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## Dinosaur (Jan 29, 2004)

It might depend on the tube. Some tubes eventually start to tear at the intersection of the valve. You can try to be a little more light handed when you disconnect your pump head from the valve stem. I hold mine with one hand while pulling off the pump head with the other. I use threaded valve stems also. I stopped using Performance brand tubes and that just about cured my problem. It could also be the wheel rim. Some wheels have small holes for the valve stem. You can put an extra layer of tape around the rim hole, or drill it out to make it larger. Going to a heavier tube will probably solve your problem. The threaded valve stems do get hung up a little when being disconnected, but when I went to a different tube my problems (in that area) stopped. Untheaded tubes will probably work also, but they are more expensive. Check with your LBS and see if you will cut you a deal if you buy tubes in bulk.


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## iliveonnitro (Feb 19, 2006)

Einstruzende said:


> If you use the "nut" on threaded stems, don't.


+1. Don't use the nut that's given to you with the tube.


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## wim (Feb 28, 2005)

Creakyknees said:


> When removing, use 2 hands on the pumphead - one to hold it steady, the other to release the lock lever, then both to pull it straight off the valvestem.


That's the secret, with the emphasis on 'straight off' rather than wiggling it off.

The nut mentioned here doesn't seem to have had any effect on my tubes one way or the other. The ones that blew out on me at the valve were all from the same bulk purchase, which most likely meant 'bad batch.'


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## danl1 (Jul 23, 2005)

iliveonnitro said:


> +1. Don't use the nut that's given to you with the tube.


-2. At least in some circumstances, that nut is a great benefit. Snugged (but not tightened) it can help prevent rocking the stem back and forth while hooking / unhooking the pump, reducing wear at the connector.

What these guys are really saying is, 'don't overtighten the nut.' That said, it's not at all necessary and I seldom use one, since most of my rims are fairly deep. In that case, it doesn't have the advantage it otherwise would.

- Also, don't use longer stems than necessary. Increases the stress on that joint.

-If you use CO2, make sure to have the cylinder perfectly vertical and release the gas into the tube slowly. If you go too fast or at an angle, liquid C02 can splash up into the stem. When it hits rubber and then boils off, it instantly freezes the rubber, cracking or at least weakening it. 

-If using a minipump, lay the wheel on the ground, put a foot, a rock, or some other object under the pump head and go at it. Alternatively, support the wheel by hanging it from one hand while pumping with the other. That's half as fast and twice as hard, but if it's wet and muddy, sometimes it's what is needed. NEVER use a handpump with the wheel attached to the bike. That's just begging to pull a stem loose.

-When removing a pump head, loosen the lever on the head (if present), grab the rim and tire with both hands such that fingers are interlaced through the spokes and there's a thumb to both sides of the rim, pushing the head straight off. Don't try to wiggle and twist it off.

-Before installing the pump head, give it a bit of lube. Loogie is the approved lubricant for this application. 

-Raid the office supplies at work for a box of 'paper reinforcers', the little round stickers meant to keep papers in their binders. They'll help protect the spot in case you don't get the hole smooth, clean and protected by the rim strip, as mentioned previously. Better still, put a small piece of electrical tape over the inside of the hole, punch through it with a pen or knifetip, then insert the stem.


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## Kuma601 (Jan 22, 2004)

There is likely a burr on the valve stem drilling that is puncturing the tube. Some sandpaper, file or countersink to clean that edge up should be the solution.


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## High Gear (Mar 9, 2002)

CHRISTO said:


> I keep getting leaks at my valve stem/tire junction. I suspect a lot of the problem is the threaded valve stems. I've got to work it out of the pump fitting whenever I air up the tires and it weakens the stem. I'm going to threadless to fix that. Any other suggestions to help? Thanks


If your using crap tubes, this is your problem. Stick with a name brand like michelin or Vittoria and you should have NO problem.


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## John Nelson (Mar 10, 2006)

I think the problem is most likely related to how you apply and remove the pump head. If you are using a frame pump, it may also be related to how you pump.

I use the nut when pumping, but then back it off.


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## sdjeff (Sep 4, 2008)

*Get a different pump*

I had that problem with my old floor pump (that had only been used on Schrader valves for about 2 years). Got a new floor pump with a different style head (Joe Blow Sport) and it slips right on and off, no wiggling required, locks on with a lever. Seems to be a function of how tight the rubber seal is when the locking mechanism is released. 

Now with my frame pump this last weekend, I actually snapped the threaded valve stem (yes, the whole stem, not the valve or the rubber) about 1/2 way down when I tried to pump like a gorilla...


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## jmlapoint (Sep 4, 2008)

IMO the reason for most presta valve stem/rubber failures is due to the size of the hole in the rim.
I used to have lots of rubber failures at the base of my stems. When I looked carefully, some of the rim holes were too big, and some were made for schrader size stems.
If you look carefully at any presta valve stem, threaded or smooth, the main shaft measures 6mm exactly. At the base of the stem is a collar with tube sandwiched in between. This collar measures exactly 7mm. What you want is for your stem to slide through the rim hole, but have this metal collar flush against the hole and not protrude thru. That way you have a metal collar against the rim hole and not the rubber. If the rubber touches the rim hole it is prone to failure. If the rim hole is large (schrader size) the stem and rubber will protrude into the hole and fail for sure. If your rim hole is too large and the collar slides thru, you can use a very thin washer that you slip over the stem and down against the collar. Then when you put the stem with washer into the larger rim hole the washer stops protrusion and again you have metal on metal and the fragile rubber is not rubbing the rim hole.
Having said all of that, you can occassionally get a tube with a defect at the stem/rubber junction, but IMO this is rare.
Since making sure my stem 'collar' abuts the rim hole and doesn't pass thru, I have not had a failure at that location for years.
Sorry to be so long winded.


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## Pieter (Oct 17, 2005)

I have fixed a tube when the stem loosened. Low viscosity (like water) cyanoacrylate. Haven't had the guts to try it at high pressure for extended riding though ;-)


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## gande_bike (Feb 28, 2006)

+1. I had the exact same problem on a set of Spinergy's - which stunk for a whole host of reasons including the oversized hole. I had to fabricate an overlay with a smaller hole to stop all of my tubes from popping. That fixed it.


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## PaulRivers (Sep 11, 2006)

I had that problem for a while, but that was because I was putting the tires with the skinny stems on a rim that was made out for the big fat stems. (One is schrader and the other is presta, I just don't remember which is which at the moment.) Once I switched back to the bigger stems the problem went away. (Well, it happened 1 more time, but it was immediately after putting on a new tube and I think it was just a tube manufacturing defect)

If that's not the case, I would suggest the pump may be at fault. It shouldn't be yanking a lot of the stem when you take it on and off. My dad kept busting his valve stems, and once even yanked the entire stem out of the tube. He was stubborn and insisted the pump was "fine". Finally, I stole his old one and replaced it with a new one. He was a little irked, but when he no longer had constant leaks he admitted he should have given up on the old one and just bought a new one himself.

Is it always the same wheel that gets the flats, or is it both wheels?


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## ktuck (Jul 3, 2008)

I just returned a batch of tubes to Performance because they were all failing about 1/4" from the base of the valve stem. Had four flats in rapid succession, on both wheels, and haven't had any problems since getting new tubes.


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## Mr. Versatile (Nov 24, 2005)

I've had more flats this year than in any year out of the last 10 or so. I've had 4 - 5 flats from the tube failing right at the juncture of the valve. My take on it is crappy tubes. What concerns me the most is that this happened on several different brands. I use Michelins whenever I can find them, Giant, Performance, and Continental. They all failed at the same spot. I greatly prefer smooth stems. I find they're easier to clamp to the pump with a good tight seal, easier to release, and don't wear the pump head as much as threaded stems do. Michelin tubes have been difficult to find lately. I can't substantiate this, but I heard that Michelin was having problems with them, so temporarily stopped production until they could correct whatever was wrong. I wonder if it's the problem we're talking about here? BTW, I've checked my rims and they're all just fine on all 3 bikes on which the flats occurred.


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