Presta Valve Stem Threads
 

I need to know the tread pitch and tube size for Presta valve stems...the outer part that the locking nut screws onto. I've searched but could only come up with one answer...and that was not 100% positive. Looking to see if anyone can confirm it to be 4mm x 0.80 pitch.

Thanks.

Dan

http://www.bikeforums.net/bicycle-me...ize-pitch.html

Looks like it's not metric.

Wikipedia says this.

The external threads at the tip of both "threaded" and "unthreaded" Presta valves are M5 x 1.0. The external threads on the main body of "threaded" Presta valves are M6 x 0.75.[citation needed]

I tried.

stem is 6mm in diameter, * you can count thread per CM and divide by 10 to get how many per MM.

*per my caliper

All the threaded Presta valve stems I've encountered have been 6mm x 1mm.

+1
I just measured one with my thread gauge.

The cap threads are >4mm.
My only 5mm gauge is a 5X.8
It screwed on about 2-1/2 turns and bound up. Ditto with the plastic cap on the male gauge.
The cap screwed on all the way on a 10-24 male, but was very loose.

Just curious, why?

I can state for certain my Presta valves are not M6x1.0. I have bins full of M6 nuts and bolts, and the nuts absolutely do not thread onto the stems. The pitch is way finer on the stem. All of the machinist sites seem to agree that the pitch is oddball-- but none seem to agree on what the threading actually is: like metric 0.6 or 0.8 pitch or something between 36 and 40tpi. The size/pitch of the threading on the core is even more elusive.

Highly likely that the threading on Presta valves is unique to Presta valves.

I'm fabricating some valve extenders. I'd made a few previously, but I never actually bothered to look at the size of the tap that I used...and now I've lost it and need to get a new one. I know I can buy valve extenders, but there's a couple reasons I make my own. I've actually purchased some of the Continential brand...didn't work well. And, I make them out of a flexible tubing to make using frame pumps easier. On a few occassions I've broken valves stems when pumping up to pressure because the stem gets torqued around. The flexible tube prevents that.

Dan

FWIW , thread pitch gages are part of a Machinist's tool box.


a Pump head on a short piece of rubber hose, and another PV stem out of an old tube held with a Hose clamp.

should isolate the stem from a ham fisted handpump operator .

Concur...that's pretty much my plan. Except...I could use hose clamps. But I just want it to look a little cleaner, professional so I'm going to thread it.

Dan

According to Wikipedia. "The external threads on the main body of "threaded" Presta valves are M6 x 0.75 ". Don't know if this is correct or not but worth checking out.

Tubeless presta nut woes
 

on tubeless the bikes the nuts are more important to keep the valve stem in place

but they always come loose and leak

so what I would really like is an aircraft type nut to keep them in place...

anyone have some ideas??

Maybe the usual substitute for self-locking nuts, a thread locker like blue Loctite 242 nut and bolt thread locker?