A tubeless valve stem is a tubeless valve stem, right? Not so fast. When it comes to tubeless valves, Nex-Gen Sports claims that all are not created equal. Rather than being constructed from “thin wall, welded or extruded aluminum tubing,” Nex-Gen Stem Gems are machined from solid bar stock which is just the start…

Nex-Gen Stem Gems tubeless valve strength


Starting with cold drawn solid bar stock, Stem Gems are CNC machined and then put through a “multi-stage anti-corrosion process that exceeds both American STM B117 and ISO/DIS 11130/2017 international standards.” Seemingly through their own testing, Nex-Gen claims that their valves are up to 200% stronger when compared with five other brands of extruded valves with similar lengths and identical wall thickness.

Nex-Gen Stem Gems rubber grommet Nex-Gen Stem Gems valve head

To make the sealing components more durable, all of the rubber pieces are removable and replaceable. The ends also feature a 4mm Allen fitting to help tighten them to the rim when first fitting them. Nex-Gen claims the alloy head of the valve stem is specifically engineered to work with their tire sealants without “causing ‘balling’ of the sealant ingredients.”

Nex-Gen Stem Gems weight

Offered in 42, 62, and 95mm valve lengths, actual weights start out at 4.7g for the 42mm valve with the cap. Sold as a pair in all black with a clear cap, the Stem Gems sell for $19.99.




  1. Seraph on

    I use Stan’s regular alloy valves. Never had an issue with them. I’m not sure that tubeless valves is a great place to try to innovate.

  2. J Jones on

    Absolutely nothing new. The VAST majority of valves are also machined from billet so that’s a hollow claim, made against mystery brands. Many many valves have removable seals and the balling of sealant has nothing to do with the metal, it’s a result of the chemistry of individual sealant and not an interaction with an anodized surface.

  3. Tom on

    In my limited experience, strength of the valve stem is not an issue. Clogging of the valve seat is, but its endemic with this type of valve with sealant. Boutique item that offers no advantage, in search of your cash.

  4. Chris Stenger on

    Its the inner valve parts bending that they need to fix IMO.. (the skinny threaded part) i always start bending them and then you can’t close the valve as good and you loose a tiny bit of air…

  5. Crash Bandicoot on

    Hmm interesting, I always go Chinese anodized ones on ebay and have never had an issues. When I did the brass ones I’d throw them in the ultrasonic cleaner for a few minutes and the congealed sealant was no more. Pro tip, once you can’t patch your road tubes anymore, extract the valve stem. Been doing that for years and have never had to buy a valve stem.


COMMENT HERE: (For best results, log in through Wordpress or your social media account. Anonymous/fake email comments may be unapproved or deleted. ALL first-time commenter's posts are held for moderation. Check our Comment Policy for full details.)

This site uses Akismet to reduce spam. Learn how your comment data is processed.