Help! Presta Noob having prolems pumping up tyres

[chugsy]

Hi All,

I recently acquired a new commuter on the C2W scheme at work but have held off on using it for commuting until I got some Marathon + on it. I've never had presta valves before and had problems last night pump up the tyres beyond 50 psi. I use a screw on presta/schraeder convertor valve and a Zefal Rush Plus trackpump. It does not have a locking lever at the head, just a spring loaded clip which grabs the side of the valve. Pumping is fine up to 50 at which point air starts blowing out with each stroke although it is possible to continue pumping. Anyone have any tips or is it time to bin this 10 year old pump? Feeling a bit skint TBH after being forced to upgrade tyres on a new bike


Also, any tips on using external pressure gauges? My cheapo digital gauge from tescos works great on normal schraeder valves but I can't stop the presta valves (with convertor) from loosing air as I hold the gauge over it - don't know if this alters the readings or not

Cheers

 

[ChrisKH]

I think it's time for a track pump with a gauge. Yes, they're relatively expensive but make a good choice and they last forever. Well, a long time.

 

[MajorMantra]

Get a new pump. If your current one is 10 years old it's likely the seals have perished. You don't have to spend a great deal on a track pump but get one with replaceable parts in the head as you can wear the important bits out in a year or two of regular use.

Matthew

 

[chugsy]

Current pump has a gauge (although it's a bit off - just add 15 ;D) and i believe the leak is between the adapter valve and the connection on the hose. I'm feeling a bit tight and would prefer to hold off on a new one. I did see this however at JE James when I was picking up the bike:


Anyone have experience of it? Seemed sturdy enough...

http://www.jejamescycles.co.uk/rsp-alloy-floor-pump-with-oversized-gauge-id46263.html

 

[Globalti]

Check that the head on your present pump isn't just coming unscrewed, allowing the leak.

Be careful when buying a track pump that the barrel isn't fat for MTB tyres - you will need muscles like a gorilla to pump up a road bike tyre!

The Joe Blow Topeak is pretty good for both types.

Once you've got a track pump you have the right to call yourself a proper cyclist.

 

[killiekosmos]

Check that the head on your present pump isn't just coming unscrewed, allowing the leak.

Be careful when buying a track pump that the barrel isn't fat for MTB tyres - you will need muscles like a gorilla to pump up a road bike tyre!

The Joe Blow Topeak is pretty good for both types.

Once you've got a track pump you have the right to call yourself a proper cyclist.

+ 1 for Joe Blow

Also get some CO2 cartridges for emergencies

 

[ColinJ]

I know this probably sounds obvious, but you are unscrewing the little knurled thingy on the end of the presta valve first aren't you? And also - depressing it so that some air comes out - the innards of presta valves often get stuck and you need to free them up before trying to pump more air in.

If you aren't, then you are probably not getting any air into the tube and eventually the pressure build up in the pump is what is causing the leak.

 

[chugsy]

To answer Globalti, the head on my track pump simply clips on via a spring mechanism - works fine up to 50 PSI, after that I guess it can't maintain a decent seal against the valve...

Colin - knurled nut is all the way out. As I said before, I can keep pumping but alot of the air escapes after 50 PSI.

Can anyone tell me how the Joe Blow head mechanism attaches to the valve? Do modern track pumps have a lever arrangement like minipumps?

 

[chugsy]

Never used CO2 but would only consider it if I can screw the dispenser directly to the valve - presta or adapter.

 

[ColinJ]

Colin - knurled nut is all the way out. As I said before, I can keep pumping but alot of the air escapes after 50 PSI.

Okay, it's out - but did you press it in before trying to pump the tube up, as described above?

When you are pumping, if you listen carefully, you should be able to hear a little 'tick' from the valve as it opens and closes with each stroke of the pump. You also feel the pump handle 'give' as the air is forced into the tube..

I suspect that your valve might be jammed in which case you won't hear that noise when you are pumping and the action of the pump will feel very hard until the pressure starts to leak out.

50 PSI really isn't a high pressure so you shouldn't have leakage problems. I have had problems at 100+ PSI, but never at 50.

 

[chugsy]

I'll try it again tonight when I get home - thanks for the tips Colin!

 

[ColinJ]

I'll try it again tonight when I get home - thanks for the tips Colin!

That's okay. Even if that advice doesn't sort the problem out for you, it might help someone else. I've given the same advice to quite a few people before who hadn't realised how presta valves work and what problems you can have with them.

I'd be interested to know whether that's what the problem is, so be sure to let us know when you have tried it.

 

[chugsy]

Sure thing - one last question... I guess I have to deflate the tube completely each time to depress the pin to get it into starting position? Might the fact that I was pumping up with the valve at 12 o'clock make the difference?

 

[ColinJ]

Sure thing - one last question... I guess I have to deflate the tube completely each time to depress the pin to get it into starting position?

Nope, why make more work for yourself - you'd only have to pump the tube back up again!

You only have to depress the end of the valve slightly until a little blast of air comes out and that is enough to tell you that you've freed the thing. Let the minimum amount of air out that you can. I just briefly press the end of the valve with my finger. You can often feel that the valve is stuck and then when you press a bit harder it finally gives way. If you think about it, you'd have to use an awful lot of air pressure to push the end of the valve as hard as you can with a finger.

Might the fact that I was pumping up with the valve at 12 o'clock make the difference?

That's the position I usually choose. I don't think it would actually make a lot of difference in your case because you have a screw-on adaptor which should stop the end of the pump flopping against the end of the valve and letting the air out.

I have to be careful with my pump though because it clips directly to the valve and if it isn't on straight it it can sometimes accidentally depress the valve.

 

[chugsy]

In my mind I thought the pin had to be "in" the valve to syncronize the push pull with each stroke of pumping. Home time soon...