If there’s one component on your bike that hasn’t seen much innovation over the years it’s the humble valve stem. Not that it didn’t need it, but with so many off the shelf options available, wheel manufacturers simply had to spec something that met their cost requirements and matched their rim bed’s shape close enough. There was little impetus to fix something that didn’t seem broken. But, when we need things like compressors and 160psi auxiliary chambers to blast enough air into our tires to pop them into place, perhaps things were “broken”.
Fortunately, our friend Wayne at Legion saw the opportunity and came up with a unique design that more than doubles the amount of air that can flow through the valve stem. And he claims this new design will let you seat a tubeless tire with any standard floor pump…
The new Legion VMAX tubeless valve stem replaces the traditional core with a hollow one that opens up to two large cutouts inside the stem. The nut on top threads up to allow it to press down and create an open airway. Thread it down and it pulls it up to close off the system. A rubber seal at the bottom prevents air from leaking out, and when the tire is inflated, that internal pressure pushes the core upwards to maintain the seal until you (or your pump) presses it down. Basically, it’s the same way a normal Presta valve stem works, but this one has a MUCH bigger airway. Here’s a look inside:
The system is completely proprietary, so you can’t just replace your valve stem’s core with this one, but they’re sold in pairs as a complete system so you’ll just replace your standard valve stems with these.
Wayne tested them to prove the difference, showing a 275% improvement in air flow. So, basically, these valve stems allow almost 3x the air volume to move through them, so you no longer have to remove the cores to try to maximize flow. Which means once you do seat them, they’ll stay inflated.
Wayne says you’ll be able to seat normal road tubeless tires (and gravel, cyclocross, and some smaller mountain bike tires) with a standard floor pump now. Large volume mountain bike, Plus and Fat Bike tires might still need a bigger push, but there’s other reasons to use them for MTB.
The design leaves a small tube attached to the backside, which keeps sealant from settling into the valve and clogging it up. And, at least for road bike tires, it should allow you to use a syringe to check sealant levels. The larger opening also means you can easily add more sealant without having to remove the valve core.
Retail should be about $30 for a set, and they’ll include small covers to keep crud from getting trapped in the core’s air passage.