Inflating to 125PSI - Kenda Tube

[Poolcue]

Hi folks, Another beginner question. i just bought a track pump from my LBS and went about inflating the tyres on my road bike to the correct pressure. The tyre wall says 125PSI on the side so i figure i should be aiming for that pressure.

However, when i get to about 60 PSI the tube / tyre will not allow any more air in and the pumps pops off. It is Presta valves that i have on my tyres. I've read the Sheldon Brown pages about having the valve open and i seem to be doing this.

Any other ideas...... Or am i missing something obvious?

 

[John the Monkey]

What pump do you have? Is it on the valve properly? Is it getting air into the tube?

 

[Poolcue]

It's just a bog standard track pump which claims to inflate to 160 PSI. It seems to be on the valve properly, im really keen to get out tommorow, need to work this out first obviously.....

 

[Landslide]

It may be that the pressure guage on your track pump isn't very accurate. I'm guessing that if you're aiming for 125psi then you've got skinny road tyres, in which case aim for a pressure where you can only just about deform the tyre a bit by pressing into it with your thumb.

 

[Gerry Attrick]

I reckon that the valve coupling on some pumps does not grip the valve tightly enough, particularly if the rim is fairly deep and only a relatively short portion of the valve is available to which to attach the coupling. Easy answer is to get someone to hold the coupling on whilst you operate the pump.

When you change the tubes, get the type with a fully threaded valve stem as a firmer grip is offered to the coupling.

 

[mickle]

Have you pulled the lever?

 

[Ivan Ardon]

+1 for Mickle. It's lever up on track pumps, the opposite way to a car footpump.

 

[upandover]

My track pump (from Towsure!) did the same, popping off at around 100psi. I spent a while getting my wife to hold it on, but soon got fed up (though my wife got fed up first...

One solution. I picked up an alternate attachment end from Decathlon for about three pounds. I simply cut the tube next to the standard end (the bit which goes onto the tyre) and fitted the new one with a supplied clip. Works great.

I did try an extension piece first, which gave the pump more to grip, but to no avail.

Cheers
Steve

 

[alecstilleyedye]

I reckon that the valve coupling on some pumps does not grip the valve tightly enough, particularly if the rim is fairly deep and only a relatively short portion of the valve is available to which to attach the coupling. Easy answer is to get someone to hold the coupling on whilst you operate the pump.

When you change the tubes, get the type with a fully threaded valve stem as a firmer grip is offered to the coupling.

or get tubes with a 51mm valve.