Valves are one of those bike components that most riders rarely think about. They tend to do their job without complaint - until tubeless sealant clogs them up and they stop working properly. Believing the traditional Presta valve design could be significantly improved, the engineers at Stan’s invested considerable time and effort into developing the Exo-Core valve. But with a price tag that’s hard to ignore, are Stan’s Exo-Core valves really worth the investment? Dave Jones put a set through their paces to find out.
“Built upon 20-plus years of tubeless evolution and meticulously engineered, the revolutionary Exo-Core Tubeless Valve delivers unrestricted sealant application and unparalleled airflow when setting up tubeless tyres.” The problem with trying to design an updated Presta valve is partly that you’re battling against more than a century of history (they were invented at the end of the 19th Century by Frenchman Etienne Sclaverand) and partly that their size is essentially fixed as they have to fit through a 6mm diameter in the wheel rim. Traditional Presta valves come in five parts – a hollow metal shaft, a core which moves to allow air in/out, a lockring to help keep the shaft fixed rigidly to the rim and to prevent air loss and a cap to cover the valve to help prevent dirt getting in/air leaking out.
Stan's Exo-Core valves share the same five basic components as a conventional Presta valve, but it's the redesigned core that sets them apart. With a standard Presta valve, removing the cap reveals a small threaded valve core that must be unscrewed to inflate or deflate the tyre. This core moves up and down inside the hollow valve stem, opening and closing the air passage. The Exo-Core system takes a different approach. Instead of a threaded cap, it uses Stan's press-fit "Tap Cap", which simply pulls off. To add or release air, you unscrew the upper section of the valve housing rather than a tiny valve core. Because this section has a much larger diameter than a traditional Presta core, it allows significantly greater airflow while also making the valve far less prone to clogging with tubeless sealant.
All of this innovation comes at a cost. A pair of Stan's Exo-Core valves carries a recommended retail price of £50 - around five times the price of a typical set of quality Presta valves. That inevitably raises the question: do the performance benefits justify the premium? We asked Dave Jones to put them through their paces and find out.
The problem
Although I’m a keen gravel rider, in the winter I do a lot of cyclocross racing and I had a big issue trying to get my CX wheels/tyres set up tubeless. I hoped the Exo-Core valves would be the solution to my problems. My cyclocross tyres (Schwalbe x-one All-round/Bites) are such a tight fit on my Scribe 365 rims that when I use my Airshot to seat the tyres, as soon as I let the air out (no matter how slowly I do it) so I can replace the valve core, the tyre unseats from the rim. I've tried inflating them to 100psi and then leaving them overnight to stretch the beads, but they still pop off the rims as soon as I disconnect the Airshot.
The Solution
Stan's Exo-Core valves have a unique valve core that allows the high pressure burst of air from the Airshot to inflate the tyre without having to remove the core. Once the tyre was fitted on to the rim, I unscrewed the core to add sealant, then replaced the core and screwed the Airshot onto the valve head. I then inflated the Airshot to 140psi then released the pressure into the tyre which seated onto the rim straight away. Next, I unscrewed the Airshot and the valve core did its job and kept the air in….job done.
Last season I ended up racing on mixed terrain tyres even in muddy races solely because I couldn't cope with the hassle of changing tyres. Now that I have Stan's Exo-Core Valves fitted to my CX wheels, I have no excuse to race on the wrong tyres next season!
If you've been battling stubborn tyres that refuse to seat properly, or you're constantly dealing with valves clogged by tubeless sealant, Stan's Exo-Core valves could be the solution you've been looking for. While they're undeniably expensive, the improved reliability and hassle-free setup they offer may well justify the premium. If they let you run your preferred tyres without the usual frustration, they're an investment that's easy to appreciate.
Stan’s Exo-Core valves cost from £50 per pair and are available from most good bike shops.