Silca’s new Presta valve extenders’ clever use of elastomers and sealants put an end to the annoying rattle inside the rim hole and prevent air leaks.
On the outside, an elastomer ring is designed to sit snugly inside the rim’s valve hole and hold it firmly in place. That prevents it from rattling around until your nerves are shot, and it’s a good sight more attractive than electrical tape. You’ll need to measure the distance from valve hole exit to the inner rim bed and figure out the difference between that and you current tubes’ valve length to make sure it all lines up, but your sanity is worth it.
On the inside, they worked with a company that specializes in thread sealing to coat the inner threads so they seal tightly against the tube’s valve threads. Then, they added elastomeric gaskets at both ends of the interface to further plug the joint. The result is no air loss. Or at least no more than you’d get with just the regular tube.
But wait, there’s more…