Presta Valve Failure?

coach22

Can some one please explain what I am doing wrong?!

This is the third tube now that this has happened on. When I unscrew the valve cap to pump up my tyres I get a hissing noise and the presta valve flys off!

I have the tyres pumped at a normal enough 100/110psi

531

The valve is unscrewing with the yellow cap. Unscrew the valve from the cap, screw the valve back into the cylinder.

Discard the yellow cap (most people don't use them, as far as I know, and they serve no useful purpose) and you should be rid of the problem.

Raam

Take the valve cap off the bit which comes off. Then slightly unscrew the little head part. Screw the entire thing back in.

Brian?

coach22 wrote: »

Can some one please explain what I am doing wrong?!

This is the third tube now that this has happened on. When I unscrew the valve cap to pump up my tyres I get a hissing noise and the presta valve flys off!

I have the tyres pumped at a normal enough 100/110psi

You're screwing out the inner core of the valve! That's mental. You obviously have a death grip on the cap when you're taking it off, because this isn't easy to so.

My advice, bin all the caps and steel washers that come with your tubes. They serve no purpose.

531

I agree with Raam and Brian?.

Why are washers and caps even included with (all) tubes?

coach22

thanks lads! ye were right! managed to take the cap off there and screw the valve back in! good to know. I binned two good continental tubes previously so!

will chuck the valve caps in the bin too while i'm at it so!

Brian?

coach22 wrote: »

thanks lads! ye were right! managed to take the cap off there and screw the valve back in! good to know. I binned two good continental tubes previously so!

will chuck the valve caps in the bin too while i'm at it so!

I'm still a little shocked you managed that by accident. I have deep section wheel so I use screw in valve extenders. The extenders come with a little tool for removing the valve core the way you did. Sometimes it's tricky with the tool and you did it by accident, 3 times!

At least you know now .

JBokeh

The conti MTB tubes do the same recently, really annoying if you're absent mindedly unscrewing the cap and end up pulling the whole valve out.

You'll notice 2 flats on the threaded part where the cap threads on, catch them with a pliers and tighten them up a bit, stops the same from happening again

Undercover Elephant

Brian? wrote: »

I'm still a little shocked you managed that by accident.

I've managed to do that with Contis in the past without putting much pressure on the cap. Some are just poorly attached. I'd suggest putting a tiny bit of grease on before rearranging it. Then you can tighten it better.

rollingscone

yup.

I was losing pressure all the time on my Vittoria tubes the trick was to use two needle nose pliers to tighten the two sections an extra half turn.

el tel

When I get a flat I find its quicker just to bin the wheels and buy new ones with tubes and tyres pre-fitted.