Originally Posted by
HillRider
However, many (most?) Presta valves will be a bit sticky when the nut is loosened and it takes a large amount of overpressure to open it the first time. The standard cure is to "burp" the valve....
Today I'd say most, however this was NEVER a problem years ago when the valves were made in Italy. It seems that the Taiwanese versions use a softer material for the seal (or have a different seat angle) and the current stuff sticks pretty badly after being closed a while. BTW- it doesn't matter if you tighten the nut or not, it's a question of pressure and time.
Another example of a new problem on something that worked for almost a century.