A picture is worth a thousand words. I’m trying to figure out how I could have caused this. I have a couple of theories. Either my understanding of valve stems is wrong and they’re tapered inside so over tightening the core can cause excess strain on the stem. Another theory is a manufacturing defect that causes the split due to the wiggling motion when pulling a tight pump off. Finally, maybe something from a trail was thrown up and damaged the stem, but I can’t remember any specific incident.
by terdward
9 Comments
Everything on your bike can be damaged from overtightening.
There’s zero need to crank on those presta valves. Just lightly turn until they stop wiggling.
That looks very deep into the valve core that valve I think it indeed has been over tightened. Valves should only be hand tight no force should be used not for the presta valve or for the valve itself or the valve core to the rim. Only other reason this has happened is if you put high force on the valve when pumping or you got pliers and squeezed. Get a new valve and valve core and this time make sure it’s only hand tight no force required if the seal is correct over tightened valves leak more than looser ones usually.
Did you put a spanner on your valve core tool for extra leverage?
Yes.
I always just tighten them so they are snug-hand tight, with the logic of I get a bad puncture and have to install a inner tube on the side of the road I can get the valve out by hand, since I won’t have a wrench/pliers with me
It doesn’t have to be tapered to split. Too tight would basically be like trying to pull the threads on the core through the threads on the stem which would be like driving a wedge through the stem. These just need to be finger tight.
I really like the combo valve cap/core wrench (on right side in pic) since it’s easy to have with me and makes it very difficult to overtighten since the lever is super short.
I’ve also had split valve stems, but not since I use a proper tool to insert and remove cores.
https://preview.redd.it/3t2y3rx9sboc1.png?width=663&format=png&auto=webp&s=3d7d9363c25c9ca268809939462fa94b53dfc681
I keep my valves finger tight and tighten my valve cores with a tool built into the valve cap just until the valve itself wants to rotate. Has always worked just fine.
it appears so!