Presta valve question

[Kano]

Why'd this happen?

On the presta valves, there's these nuts that screw down to the wheel. I suppose they're for stability, and that's probably a good thing, but why were mine screwed halfway up to the "business end" of the valve? How did they do that?

The only different thing that's happened to her lately was the ride on the car rack, and I don't see how this could affect the nuts? I'll keep an eye on them, which should be easy to do since I check the air every ride, but is this an okay occurrence?

Karen in Boise

[Mimosa]

I allways remove those nuts.

Why? If for some reason (for instance the outertubes slides due to a big surface resistance) the innertubes slides a bit then the nut will cause the innertube to rip at the valve. Without the nut the valve will move slightly in the tube but you will see that since the valve is sideways but at least you don't run a flat.

[KnottedYet]

And you can make cool jewelry out of those nuts. (and out of chain sideplates, and out of presta-schraeder adaptors, and spoke nipples, and...)

[SalsaMTB]

Sometimes I leave mine, sometimes I remove it, it just depends on my mood and if I remember to put it on. That being said, I've never had a problem when I left it on. As to why the nut slid up the valve a bit...is there any chance you put more air in after you screwed in down? As you put more air in, the valve will protrude more so you have to be sure to screw it down when you're done. If that isn't the case, I have no clue why it would move.

[SadieKate]

Those frickin' nuts always loosen up at some point. I can really only think of two reasons why they exist. 1) To pull the valve up into the hole as much as possible but you don't need this if you know how to inflate a tire from 0. 2) To keep the stem centered in the hole. Well, install the tube properly with the stem centered up to begin with. The tube doesn't move around if kept inflated properly.

I've also heard of people tightening the things till the valve stem patch rips. Just toss the thing at Knotted.

[Kano]

Sometimes I leave mine, sometimes I remove it, it just depends on my mood and if I remember to put it on. That being said, I've never had a problem when I left it on. As to why the nut slid up the valve a bit...is there any chance you put more air in after you screwed in down? As you put more air in, the valve will protrude more so you have to be sure to screw it down when you're done. If that isn't the case, I have no clue why it would move.

They were down when I got the bike, then they were WAY high up when I went to put air in, so I screwed 'em down, then added the air. Just gently hand tightened 'em. But, I won't worry about 'em coming off again, sounds like they're not critical!

Hmm, Knotted, I've got two nuts, I could make a pair of earrings!

Karen in Boise

[spokewench]

They do not come in handy until you need to change a flat on the road. Then if you are using a pump, they really help hold the stem in place while you are trying to pump up a totally flat innertube!

I usually don't have them on my bikes, but I usually do carry one in with my tire changing equipment. Screw it on when I am pumping if I am using a hand pump.

[HillSlugger]

Why'd this happen? How did they do that?

I think it's all to do with vibration.

I've thought about removing them, but I think they help keep the valve stable while applying the pump, etc. My solution was to buy some small o-rings that I can slip onto the valve and snug down to the nut.