Presta Valves - What am I doing wrong?

[PBancroft]

OK, so I got my new bike last week. I love it - but the tubes are Presta valves, and I've never used them before. I figured I should acquaint myself with them... and I seem to be incurring problems.

First off, I'm using a hand pump. I know I should get a foot pump with a gauge, but after the expense of the new bike I simply couldn't afford it. However... Every tube I've tried, I could pump it up to a certain pressure, but no more. Not as firm as the other tire, but firm enough. Fine - I remove the pump only to find the screw and nut on the end of the core is missing - sheared off. I'm fairly confident I wasn't wiggling the pump around THAT much.

This has happened on three tubes, I've just used my last one. I'm kicking myself, I really am. I now can't tighten the nut to restrict airflow. I would suspect that the airpressure would hold the valve shut, but even if so, I wouldn't want to commute on it too far, and I would want to know what I'm doing wrong anyway!

 

[orienteer]

Depends what kind of connector you're using: mustn't bend the valve at all while the connector is on or it will break.

Best ask your bike shop for advice as to a suitable pump.

 

[Auntie Helen]

Uncle James bought a widget from CRC that is a valve adaptor from Presta to Schrader: http://www.chainreactioncycles.com/Models.aspx?ModelID=20339. Seems to work well and he doesn't have the fear of bending the valve thingie, plus can use our Schrader pumps.

 

[gf1959]

I used to have nightmares with prestas and ordinary hand pumps,struggled like hell to get enough air in and the valves kept bending. The cure? A Joe-blow stand up pump,well worth the £25 or so,you won't regret it. Sometimes there's initial resistance to the air going in i find,but after a few seconds no problems. Never damaged a valve since.

 

[PBancroft]

Thanks all. I like the look of the adapter.

Will I be able to ride with the broken stem? Am I correct in thinking that the air pressure will keep it shut - or is it not worth the risk?

 

[alecstilleyedye]

i find it's easier if the valve is at 12 o'clock, as then you have gravity to assist with getting the pump off.

i'd definitely get a track pump (don't bother with a foot pump, they're less useful), will get you up to 100psi+ in seconds.

 

[gbb]

A few things spring to mind...
Are they cheap innertubes?
I've had the odd one which has bent the screwed rod. Ive had the odd one (Vittoria) which has had the core come out (they're designed to do that, but not in normal use). Never had one snap off tho.

Is the pump cheap ?
Some are better than others, particually in the pressure they can achieve. Ive got a Zefal frame pump which is quite good for the price. It cant compete with a track pump, but for £5 at the time....more than adequate.

To be a bit easier on the valves, the Zefal (and most others) have a plastic nut around the bit where your valve goes in. I release that nut a bit so the rubber grommet isnt compressed so much, slide the valve in, then tighten the nut up. This locks the pump to the valve without forcing it. Undo the nut slightly when releasing it from the valve. (make sure you tighten it back up once done. Lose that plastic nut...your pumps useless)

Not really connected, but when i've undone the little nut on the valve...i just push the valve momentarily as though you were letting the tyre down...just for as second. Sometimes they can get a bit sticky, making it difficult to inflate the tyre.

Lastly, i hold the head of the pump in the palm of my hand when its on the valve, then place my thumb on the top of the tyre (above the valve). This helps to lock the pump on and support everything while you're inflating.

 

[PBancroft]

It was a cheapish pump... £12.99 Topeak. They weren't cheap inner tubes, which is why I'm annoyed. I did burp the tube before pumping.

The air seems to be staying in the tire - not had a chance to go out for a ride though... don't know whether to risk it for the commute or not.

 

[GrasB]

On the road I use a Presta to Schrader adaptor with a Schrader pump, it just gives the valve that little bit more protection from the pump when taking it on & off but when at home I use a decent Presta track pump.

 

[GrasB]

Which may or may not snap it, best not to bend it in the first place.

 

[PBancroft]

You can bend the valve back into position with a pair of pliers.

Thanks - definitely worth knowing. The valve is straight, but the but the end of it with the pin which allows airflow, and the nut which holds it in place, has been sheared off.

 

[bad boy]

sounds like you do need to invest in a foot pump.

Most lbs have pumps out for people to just pop in and pump their tires up if you cant afford one right now just cycle by and use theirs for the time being.

 

[Crankarm]

sounds like you do need to invest in a foot pump.

Most lbs have pumps out for people to just pop in and pump their tires up if you cant afford one right now just cycle by and use theirs for the time being.

As already stated you need a track pump. (Not a foot pump - they are crap). You can get a decent Specialised or Joe Blow track pump or similar for about £20-30. You will wonder why it took you so long to buy one. They are the business for pumping up bike tyres and enables you to get them to your desired pressue quickly and without damage to your valve.

 

[byegad]

Thanks - definitely worth knowing. The valve is straight, but the but the end of it with the pin which allows airflow, and the nut which holds it in place, has been sheared off.

I did this on Prestas for years.


Solution?



Easy drill the rim for Schraders. People will tell you they don't work well at high pressure but I've got a bike with reasonably narrow tyres, 28mm, and pump them to 120psi with my track pump. They hold that pressure very well. needing topping up as with any tyre but not more often.

 

[PBancroft]

As already stated you need a track pump. (Not a foot pump - they are crap). You can get a decent Specialised or Joe Blow track pump or similar for about £20-30. You will wonder why it took you so long to buy one. They are the business for pumping up bike tyres and enables you to get them to your desired pressue quickly and without damage to your valve.

Bought myself a track pump yesterday - haven't tried it yet. The old tube seems to be holding its pressure well, so as long as it lasts until the weekend, I'll switch the tubes then... fingers crossed.