Why do presto valves exist?

[Tynan]

never had problems with either

someone's got gorilla hands I reckon

 

[walker]

Sounds like cheap tubes BTFB. Most decent tubes are pretty much welded to the valves.

 

[domtyler]

I had this problem when I bought a batch of crap tubes, drove me absolutely mad, thought it was me or something I was doing. When all the crap tubes had gone I bought some decent ones and have never had the problem since.

 

[User482]

Only valve failures I've ever had have been schraeders.

 

[giant man]

Only ever had Prestas and find them fine, don't understand how you're tearing the tube itself BTFB, but I guess by their very nature they are more 'fiddly' thank Schraeders.

 

[Jacomus-rides-Gen]

Cheap tubes.

 

[number9scores]

...bent and damaged presta valve screw when using a dual action scotts pump. Really annoying.

 

[MrJamie]

I tore off a few valves pumping tyres up when I was over tightening up the little nut that holds the valve against the rim. It seems best to make sure its really loose when pumping the tyre and only tighten it until it barely touches the rim.

 

[compo]

Before the advent of pumps that don't use a flexible connector but just push onto the valve we didn't often have problems with the valves. I have bent presta valves pushing a pump onto the valve but have now returned to a conventional pump with a flexible connector.

 

[youngoldbloke]

I tore off a few valves pumping tyres up when I was over tightening up the little nut that holds the valve against the rim. It seems best to make sure its really loose when pumping the tyre and only tighten it until it barely touches the rim.

Leave it off , its completely unnecessary, as is the dustcap.

 

[craigwend]

hAvE YoU tRiEd....

http://en.wikipedia.org/wiki/Dunlop_valve

 

[Rickshaw Phil]

Is this a record for thread resurrection?

 

[Mr Haematocrit]

I have had enless problems with these long tall presto valves.

How long are we talking here, I use 80 mm valves on my clinchers without the rim nut and have never experienced the issues you mention. What make are the tubes?

 

[Rickshaw Phil]

How long are we talking here, I use 80 mm valves on my clinchers without the rim nut and have never experienced the issues you mention. What make are the tubes?

Bigtallfatbloke was last seen:4 Feb 2010

You might not get an answer to that question.

 

[Foghat]

Leave it off , its completely unnecessary, as is the dustcap.

Actually, if it isn't overtightened, it's rather useful as a way of reducing stress on the valve/tube join, which can be quite high every time a pump head is forced onto the valve - this is because it uses the rim to resist the pressure rather than the delicate tube material at the interface between valve and tube.

Repeated stress at this join can lead to failure - especially in cheap butyl tubes. The problem is probably even more likely in delicate latex tubes - in the past I've found that Vittoria latex tubes frequently failed in this way, even with the nut in place, so it shows how critical the valve/tube join area is to tube integrity and emphasises why it is good not to stress it any more than necessary. Ever since, I have treated tubes very carefully when pumping, due to the fact that these failures usually occur with sudden rapid deflation, which could be catastrophic on a fast winding descent; it also means I don't trust latex tubes an inch any more and never buy them now.