Help - Constant splitting tubes at valve shaft !!

[dellzeqq]

excuse me if I've missed something upthread, but have you changed from Schrader to Presta?

If not, then I'm afraid that I reckon that there is wear or some small damage around the hole in rim, and, while changing the rimtape might help (I had a similar problem, and I've 'fixed' it by using two rimtapes, a woven and a 'plastic' one on top of the other) you might be looking at a new rim.......

 

[HLaB]

I put it to you that you are failing to seat the valve, and /or using the useless screw on valve lock rings which come with the inner tubes and which must be thrown away. It's highly unlikely that your tyres are spinning on the rim but the strong possibility remains that there is a burr on the inside edge of the rim 'ole remains.

It may be coincidence but the twice I've had valves snap was when I was using those valve lock rings. I don't use them any more and it hasn't happened again. The other thing I use now is talc inside the rim, it perhaps allows for a wee bit of movement in the tyre without snagging the tube.

 

[giantxtc]

I put it to you that you are failing to seat the valve, and /or using the useless screw on valve lock rings which come with the inner tubes and which must be thrown away. It's highly unlikely that your tyres are spinning on the rim but the strong possibility remains that there is a burr on the inside edge of the rim 'ole remains.

I've tried both using the useless screw AND throwing away the useless screw. It happens whatever one I use.

Regarding the burr on the inside of the rim 'ole, I've felt for this and nothing is there. Also remember I cycled with this rim for 4 years and never had this problem even once in that time so that would suggest the rim hole is fine , non? Also I've tried making all sorts of protective padding out of old inner tubes around this area, but the valve / tube slits even though these protective pads I've engineered seem to survive without a mark.

The quest continues, bought 4 Specialized inner tubes at lunch break, and a track pump to eliminate the actual inflating action as the cause. Let's see how long these last :-/

 

[ianrauk]

It only needs the tiniest of burs to puncture an inner. Sometimes even too small to feel with your fingers.

 

[mickle]

Yeahbut. Are you seating the valve?

 

[giantxtc]

Yeahbut. Are you seating the valve?

@ mickle: As this has been doing my head in for some time now, I've become a bit compulsive during the whole reinflate process. I use the locknut to hold the halve and only tighten down very gently about halfway just to keep the valve visible for inflating. I very gradually inflate checking the seating of the tyre all along the rim and that the valve remains perfectly perpendicular throughout the process. Can you expand a bit on what you mean by seating the valve? Is there another step I've been missing in my 30 years of fixing punctures . Never too old to learn something new I say.

 

[mickle]

Forgive me if any of this is teaching you how to suck eggs.

The valve stem is attached to a disc or rubber which in turn is attached to the 'body' of the tube. This disc can become trapped under the bead of the tyre unless the valve is seated.

Put one bead on to the rim.
Partially inflate the tube just enough that it retains its shape.
Pull the tyre back to expose the valve hole and insert the valve.
Fold the second bead over the tube and insert the tube into the tyre all the way round.
Starting opposite the valve gently work the second bead onto the rim (you might need to let some air out).
When the bead is within the rim all the way round push the valve through from the outside to ensure that the aforementioned rubber disc isn't trapped under the bead.
Partially inflate the tyre with just enough pressure for it to take its shape, remove the pump and check all around the tyre that its seated correctly.

You'll need to push down on the back of the valve through the tyre to get the pump head on securely. So at no point is there any need for the valve washer. Throw it away as soon as ithe tube leaves the box.

Inflate to preferred pressure.

And this: http://www.cyclechat.net/threads/mickles-tip-of-the-day-inner-tubes.85634/

 

[jonathanw]

I wish I'd come here sooner.

I had a similar problem 6 months ago. I always assumed that as the lock rings came with the tube that they should be used. Well after a similar problem to that which the OP has outlined, I stopped using them as I was reading Mark Beaumonts Americas book, and he said he'd also had the same problem because the locking was causing the valve tube interface to come under tension with a fully laden bike. Now I know better and don't use them anymore, and have not had the problem since, but I suspect this may not be the simple answer in this case.

 

[byegad]

So are you saying that some wheels will simply damage tubes? Thing is I rode this bike for 4 years without a hitch. Then since getting a regular puncture one time, all susequent tubes have failed at the base of the presta valve stem, splitting the rubber right at the bottom.

Then it's not the rim shape. Mine was new and tubes lasted anything from a few months to twenty minutes and it always went with a bang. Interesting at 30mph downhill with a lorry alongside!

 

[giantxtc]

Then it's not the rim shape. Mine was new and tubes lasted anything from a few months to twenty minutes and it always went with a bang. Interesting at 30mph downhill with a lorry alongside!

Yes byegad, the 30 mph blow out whilst neck and neck with a double decker is exactly what I'm sh*tting myself is going to happen

 

[giantxtc]

Forgive me if any of this is teaching you how to suck eggs.

The valve stem is attached to a disc or rubber which in turn is attached to the 'body' of the tube. This disc can become trapped under the bead of the tyre unless the valve is seated.

Put one bead on to the rim.
Partially inflate the tube just enough that it retains its shape.
Pull the tyre back to expose the valve hole and insert the valve.
Fold the second bead over the tube and insert the tube into the tyre all the way round.
Starting opposite the valve gently work the second bead onto the rim (you might need to let some air out).
When the bead is within the rim all the way round push the valve through from the outside to ensure that the aforementioned rubber disc isn't trapped under the bead.
Partially inflate the tyre with just enough pressure for it to take its shape, remove the pump and check all around the tyre that its seated correctly.

You'll need to push down on the back of the valve through the tyre to get the pump head on securely. So at no point is there any need for the valve washer. Throw it away as soon as ithe tube leaves the box.

Inflate to preferred pressure.

And this: http://www.cyclechat.net/threads/mickles-tip-of-the-day-inner-tubes.85634/

No worries about teaching to suck eggs, at this stage I'm willing to accept any opinions. Having thoroughly read your post I can say that I am seating the valve correctly. I partially inflate , I ensure the rubber disc is not trapped under the tyre beads, and I inflate gradually and continually check seating of tyre as I do.

Here's a pic I just took of yesterdays failed valve. It's exactly the same as the other ten, The valve splits away from the tube rubber disc and this is ALWAYS perpendicular to the direction of rotation.

 

[mickle]

I don't bloody know then.

 

[HovR]

What sort of pressure are you inflating the tires to? At this point, I think I'm just as confused as you are.

 

[giantxtc]

The only thing I can think of is something to do with the rim hole as it's always at the same point. I've just furiously attacked rim hole with emery paper and it's now as rounded and smooth as can be. Will see how it goes tomorrow.

Really appreciate everyone's input. Thanks, will let you know how I get on.

 

[dellzeqq]

go to schrader valves. Those tubes are being pushed through the hole. XM317s will take schraders