The 'Presta Killers' are Coming for your Tubeless Tires - Singletracks Mountain Bike News

Pity the poor Presta valve. It seems everyone is trying to kill it. At the Sea Otter Classic last week, we learned about three brands with new takes on the ubiquitous valve standard, which has been little changed since its invention in the 1800s. Two of the brands had their products on display, while the third is still in stealth mode and will be launching later this year.

The new Stans Exo-Core valve is clearly bent on improving how Presta valves work with tubeless tire sealant because, well, Stans is all about sealant. In 2021, Reserve was one of the first to strike a blow against the standard Presta valve, delivering thrice as much airflow as the original and reducing the chance of clogs. See also: e*thirteen Quick Fill Plasma valves, introduced in 2022.

Exo-Core seeks to up the ante by delivering not just more airflow than a standard Presta valve but also by making the valve serviceable since sealant residue tends to build up over time. Stans added a few other enhancements as well, like an unthreaded cap that pops on so you don’t accidentally unscrew the core when removing the cap. Turn the valve an eighth of a turn to bleed air or a full turn to inflate.

Like other valves on the market, including those from Cush Core, the Stans Exo-Core is designed to work with inserts thanks to ports on the top and sides that ensure a clear pathway for air and sealant whether you’re running inserts or not. It’s compatible with existing Presta pump heads, and I’ve found it has a nice, snug fit with my pump.

Finally, the Stans Exo-Core valves have an oblong and firm rubber-like plug at the base designed to fit most mountain bike rim channels. A self-locking valve nut, threaded from the other side of the rim, promises to keep the valve in place without needing a lot of extra torque.

I picked up a set of Exo-Core valves at Sea Otter and plan to put them to the test this spring. A single valve, designed for 17-26mm deep rims and including the cap and all hardware, weighs 6.8g on my scale compared to 5.5g for a notably shorter Reserve Fillmore valve designed for 18-28mm deep rims. Buyers will be able to customize the Stans Exo-Core valves with caps and valve nuts in a variety of colors. Stans Exo-Core valves will be priced at $50 for a pair.

The Muc-Off Big Bore valves promise an air-cannon-like inflation experience thanks to the unique ball valve design. There’s no internal core to get in the way of air or sealant, which promises to make mounting and filling tires quick and easy.

Like the Stans valves, the Big Bores are insert-compatible thanks to holes located in the sides of the base. The valves fit existing Presta or Schrader pump heads, depending on which version of the Big Bore you’re using. Muc-Off Big Bore lite valves work with existing Presta pump heads and deliver 230% more airflow than a standard Presta valve. Big Bore Hybrid swaps the top for a Schrader-size head on a Presta-size stem to fit most rims and deliver even more airflow, while the Big Bore Ludicrous is a full-bore Schrader that only fits rims drilled for the larger standard.

The Big Bore valves have an easy-to-use lever for opening and closing the valve, and the ones I tested at Sea Otter operated smoothly. Muc-Off says service kits will be available if you need to swap out a valve or make a repair. I love the idea of a full-open valve that doesn’t involve unscrewing tiny parts; my only fear is accidentally opening the valve too wide on the trail and instantly draining all the air out of my tire. That being said, I will be one of the first in line to give this a test!

It’s unclear how much the valves will weigh, but it’s likely they will tip the scale significantly higher than a traditional tubeless tire valve. For that reason Muc-Off suggests this probably won’t be appealing to XC or road bike riders.

Muc-Off says the Big Bore valves are patented and have been in design for three years. Look for availability beginning this summer. Pricing is TBD.

We’ll be putting these and another “Presta killer” tubeless tire valve to the test this spring and summer and will share our findings soon.