Replaceable Presta Value Cores
 

I have been using Continental tubes mainly because I can get them with 36mm Presta stems. But they have replaceable valve cores which I cannot understand there being any advantage.
Today I wanted to see how well a presta to schrader adapter worked. When I unscrewed it out came the value core. That was the second time a valve core came out. The first time it happened to me was when I took off a valve cap and the core came out as well.
So I'm now thinking maybe a bit of loctite red would eliminate future mishaps for me.

On a standard butyl tube in a non-aero rim there is generally no reason to get replaceable cores. Since I carry a Lyzene frame pump I look for nonreplaceable cores.

A replaceable core is useful if you want to add sealant to a tube, or if the core itself bends or breaks.

Are they Presta or Dunlop/Woods valve? Which can look a lot like Presta and uses the same size pump head.

Aaron :)

Other mundane brands are coming with long presta stems for aero rims now.
no replaceable valve. down to $7 retail

Yea, You might try thread locK on the valve extender removable core connection,
so when you unscrew the Pump head, the stem extension won't unscrew instead.

Woods is thicker fits in a schrader sized rim hole.

You will eventually break off one of the valve cores. I've done it several times through carelessness, and it means trashing the tube. This is not too bad with clincher wheels , but when I did that on sew-up tires without the replaceable valve core, it was a lot more costly. If you ever bend your valve core while pumping it up, don't try to straighten it. They will usually break.

I also have a Lezyne pump that threads on instead of clamping onto the Presta valve. My first time using that, when removing the pump the valve core stayed on the pump which emptied the tube. I just tightened the valve cores with an adjustable wrench, have had no problems since. I would not recommend using loctite where it could contaminate a valve seat, I only use loctite on nuts and bolts.