Presta to Schrader adaptor opinions...

[Tim Hall]

I find my woods valved tubes lose air quicker than either presta or schrader. I was under the impression that resta more more suitable to high pressure systems - did I make that up?

Lorry tyres at 120 psi (or more) use Schraeder valves, so perhaps you made it up and/or are mistaken. It's a commonly repeated statement though.

 

[mjr]

I find my woods valved tubes lose air quicker than either presta or schrader. I was under the impression that resta more more suitable to high pressure systems - did I make that up?

I'm not sure why that would be: Presta valves are held shut mainly by the air pressure differential (which is why the locknut is needed, to stop it bouncing open in use) whereas Woods and Schrader are generally spring-loaded these days.

Isn't the main reason why higher-pressure bike tyres use Presta is that they're usually on narrower rims and Presta valves are something like 2mm narrower, so there's more rim left which makes it a stronger wheel?

I can't find many comparisons of tube air-holding that uses all three valve types, but on the boxed tubes I have indoors, the Impac Woods one says to check pressure every 14 days and the Coyote Schrader box says regularly, whatever that means. I check my roadster (impac Woods) weekly but there's usually minimal change from 60f 80r - the air I have to pump to open the valve enough to get a reading seems sufficient to top it up! I check the road bike (Vavert Presta at the moment) every ride (roughly weekly) and it's usually fallen from 70f 85r to 60ish in a week. Of course, this could be Vavert being dud tubes or that my vintage bike's 28s don't run at high enough pressures to hold the valve shut, but it seems like most people top up their road bike tyres often.

 

[Milkfloat]

Maybe it is my particular tubes - I only have them on one bike but generally find I need a weekly top up at minimum. On my presta bikes I can usually get away with 10-14 days between top ups. I would have thought that the prestas would lose proportionally more because there is less volume and more pressure. Either way it is no hardship.

I like the theory about rim width - that makes a huge amount of sense, far better than my misguided pressure thoughts.

 

[HLaB]

That'd be true of all valves though.

AFAICS All valves have just got one place to lose air you are screwing another bit on top of it and introducing a second place from which you can lose air.

 

[tyred]

Unless you have skinny lightweight rims I can't think of a single reason for using presta valves.

Someone mentions Shrader un-screwing, I've never seen that happen but if it did, the basic tool (built into a metal dustcap) to re-insert it costs pennies and is a useful thing to have anyway. Ask in your local tyre centre and they'll probably give you one for free.

 

[GuyBoden]

"The smaller hole for a Presta valve makes it possible to have extremely narrow wheels while maintaining sufficient strength in the wheel."