Maybe I’m a bit presumptuos, but at least I haven’t seen it before. I got tired of my valve stem “sinking” towards the rim each time I push the pump onto the stem, so I came up with the something I call, the “Stem-lock”. It solves the problem, and the stem stays put while pushing the pump onto it; won’t budge even a bit! I LOVE IT! Can’t patent it because the clip already exists; anybody can get one! Too bad for me-great for you!
For the metal stems, there are threaded rings you can thread on, and they usually come stock. Here is the one on my 29er:
I was aware of the tubes w/metal stems, but have never seen them on a uni. Most, if not ALL uni tubes I’ve seen, have RUBBER, not metal stems.
The metal ones are called Presta valves, and the rubber ones are called Schraeder valves. Often, more expensive bicycle rims will be drilled for Presta, but Schraeder are more common because most people don’t ride the more expensive bikes and because they’re standard for motor vehicles.
Again, I have not seen the metal valve stems (aside from Unityler) on unicycles. I would be VERY interested to know if the majority of list members have rubber or metal stems on their unis, like the one pictured below. 
there are some all metal shrader stems too
The Nokian Gazz 24x3.0 tube in my Muni has a Shraeder valve and a metal stem, with the locking mechanism that Tyler’s photo shows.
I’m pretty sure that “Schraeder” and “Presta” refers to the actual valve configuration and stem diameter, not the stem material.
Yep. I was just using the language that was already at play in the thread. 
1 of 3 of my unis has a Presta valve–the one being my 29er, which has a 700c rim that was probably originally designed for bicycle use.
ANYWAY…I was only trying to help with my idea to secure the rubber valve stem while attaching the pump! GEESH! I think I’ll just keep things to myself! 
My punctured and replaced Nokian 24x3" tube had the metal valve and obviously the WTB tube in my Nimbus 29er does. My freestyle with an unknown tube (the LBS did the tire replacement) has a rubber valve and so does my current generic Muni tube. Of course my two el cheapo Torker CX’s (16" and 20") have rubber, also.
Wow. Please don’t freak out like that! We enjoy your ideas, and I had no idea that I would offend you by offering an alternative solution. I understand that would work somewhat well for a rubber valve.
my friend’s 29er has a Presta…they’re pretty sweet, I wish mine had one.
What kind of 29er do you have?
I wasn’t “freaking out”. I should have put the familiar “LOL” in there. Sometimes it’s hard to determine accurate intentions from certain posts. My bad brah. Your “alternative” is only useful if you already HAVE the metal valve;in which case it’s not even an issue. I was simply trying to show a simple fix for those who have the RUBBER stems. And I think it would be a waste of time and money to switch tubes just so you can have a threaded ring to secure a metal stem, when my idea eliminates the need to make the switch altogether 
Yep, those are called cotter pins. You can get them at a hardware store.
It would be nice if you could tell us what size fit a shrader tube. My old uni has this probem too!
I’m pretty sure that that’s a Presta valve, the same as on my 29’s tube. Mine also has the little nut on the valve stem. There are other valves with slim metal stems too; I’m told that one which I’ve seen on some Miyata unis is called a Woods valve. I don’t know much about them, though.
I like the Presta, myself. The Schrader needs a bigger hole in the rim and is harder to get into a pump nozzle.
Re: A little invention for ALL!
phlegm wrote:
> The metal ones are called Presta valves, and the rubber ones are called
> Schraeder valves.
As others have pointed out, there are all metal Schrader valves. For
pictures of the different valve type, scroll down to “Presta” on this page:
Roger
Scott uses a plastic tie-wrap around the stem to help stabilize the valve; this approach seems to work pretty well.