Presta Valve Question

[Selkie]

Could I get some advice/guidance you mechanics out there? I was inflating my front tire the other day and twisted the locknut on the presta tube open so I could put air in the tire. All the air came out of the tire in one big burst. The locknut was the whole way at the end of the valve stem. That's the first time something like this has happened. While I was able to inflate the tire, and it's still holding air, I haven't taken that bike out for a ride for fear that the air will go out once I start riding (example, if I hit a bump). Am I being overly concerned? Did I damage the valve? Should I have the tube replaced? I checked Sheldon Brown's site to see if I could find any info but was unsuccessful. Any guidance would be very much appreciated!

[Dogmama]

It was probably your thumb pushing against the end of the valve. OK, just kidding. I don't have a clue, as you can probably tell.

I think tubes are cheap peace-of-mind-insurance. I'd replace that sucker and not have to worry about sudden flats.

[KnottedYet]

The locknut was the whole way at the end of the valve stem.

I don't have presta anymore, so take my memory with a grain of salt!

I remember 2 things that would get too loose on my prestas: the donut shaped ring that held the stem in place at the rim, and the Apollo space-capsule shaped thing on the teeny-tiny wire at the top of the valve.

Guessing you're talking about the space-capsule shaped critter. I know I loosened those too much many times, then the wire bit would get off kilter and my tire would go flat. When I tightened them back down, the valve worked fine again.

When in doubt, change the tube out.

[Selkie]

Thanks! I went ahead and did a 40 mile ride on that bike today. No problems. I checked the Park Tool site and Dogmama, you might have been right. I could have pressed against it by accident, causing it to deflate. Who knew? If the same thing happens the next time I inflate the tire, I'll switch out the tube.

[SadieKate]

Mickchick, are these Michelin tubes? Some tubes have a removable valve core. If this comes out a bit too much you could experience this same result.

If the tubes have removable cores, go ahead and pull it all the way out. Put a teensy bit of blue Loc-tite on the threads and replace it. Do the same to your spare tube. You will be happy you did. Youcould be having a very slow leak as we type.

SK who has learned from experience.

[7rider]

I remember 2 things that would get too loose on my prestas: the donut shaped ring that held the stem in place at the rim, and the Apollo space-capsule shaped thing on the teeny-tiny wire at the top of the valve.

Guessing you're talking about the space-capsule shaped critter.

WOW!!!
Someone who uses my same "technical jargon"!!!
I LOVE IT!!