Tubeless Valve Test – Stan’s Exo Core: High airflow thanks to the external core!?!

Sealant for tubeless systems – that’s Stan’s real speciality. Stan’s launched its Original Tubeless Sealant back in 2001. The formula has been continuously refined ever since. To complement this, there are now also special tubeless valves designed to make the inflation process easier and prevent blockages. Their special design is also intended to allow significantly more air to flow into the tyre.

To achieve this, Stan’s uses a large core that is screwed onto the outside of the valve stem. This is also intended to make it easier to adjust the tyre pressure. Instead of pressing the core downwards, as is usual with Presta valves, you open the air flow by turning the valve cap.

The valve base has a total of 5 openings through which the sealant can flow into the tyre and past tubeless inserts.​

Stan's Tubeless Exo-Core Valve – Information

• ​Price: 54.95 euros >> Available here at a reduced price
• Weight: 6.84 grams
• Valve length: 49.15 millimetres
• Available lengths: Regular / Medium / Tall / Extra Tall
• Valve head: Proprietary system, Presta-compatible
• Drainage ports / Suitable for inserts: 5 / yes
• Special features: Air release via twist mechanism, special valve core with increased diameter, twist-and-pull cap, available in a range of colours

Assembly & Handling

​The elongated rubber seal does not fit all rim profiles perfectly. During our test with a Newmen rim, we experienced some slight air loss. The small nut is slippery to grip and is difficult to unscrew with the integrated rubber seal in place. The valve base does not have an Allen hole, which might help when screwing the valve in.

We did, however, like the tyre deflation mechanism. The external valve core is easy to unscrew and allows for precise control. The further you unscrew it, the more air flows through the valve.

Thanks to its special design, the tyre can also be filled with sealant without having to remove the core. If you want to maximise airflow when fitting the tyre for the first time, the valve core can easily be unscrewed by hand. However, even with the core in place, we were only able to press all the tubeless tyres in the test into the rim bed using pressure from a floor pump.

​Review & Conclusion – Stan’s Tubeless Exo-Core Valve

Conclusion: Stan’s Tubeless Exo-Core Valve

Admittedly, fitting the Stan’s is a little fiddly, as the knurled screw with its integrated O-ring is stiff to turn and there is no Allen key slot in the base. However, the elaborate design with its external core pays off. Significantly more air flows through the valve, and the ease of use when adjusting the tyre pressure is also a plus. You can fill the tyre with sealant even with the core in place, yet the Stan’s is less prone to clogging. Coloured valve caps offer the option to personalise it. Unfortunately, it’s quite expensive.

​This is how we measured the airflow

To find out which valve offers the best airflow, we carried out extensive measurement tests. However, the effect can be demonstrated most clearly directly on the wheel. The test was based on a 29 x 2.4-inch MTB tyre, which was inflated to 2.0 bar using a digital pressure gauge. We carried out several test runs to measure how much air escaped in five seconds when each valve was fully open.

Whilst all Presta valves – with variations of +/- 2 per cent – fall within the range of 34.1 per cent, twice the amount of air flows through the Topeak valve in the same time. With Stan’s, we measured an air loss of 78 per cent, and with Reserve, 87.4 per cent. The core-less Muc-Off achieves 100 per cent air flow; in other words, after five seconds, there was no longer any measurable pressure in the tyre. This makes it by far the best performer in this comparison.

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