Originally Posted by
happypills
~~~~ By the way have you guys ever seen a tube with a two piece presta valve? (like the top part can be screwed off)
Some tubes have a presta valve core that can be screwed out and replaced if it goes bad. It has two flats on the sides for screwing in or out with a small crescent wrench or a little plastic tool made by TUFO. I always save the valve cores from my old bad tubes as spares.