This allows Reserve to have a larger port, increasing the potential air flow, which is said to make tubeless inflation easier. Furthermore, it’s said to effectively close off the valve stem from sealant ingress, which is one of the main causes of tubeless inflation woes, as gummed-up sealant compromises a regular Presta valve’s airflow.

Reserve claims the Flowmore’s cap can be unscrewed a little and depressed to easier adjust tyre pressures. At the same time, there’s less risk of damage to the valve as it has an overall sturdier build. Finally, injecting sealant into the tyre is easier as the valve stem is less congested thanks to having no valve core, says Reserve.

Why are we excited about these valves?

We have a love-hate relationship with tubeless tyres here at BikeRadar.

Of course, we love the reduction in punctures, and their ability (often, though not always) to re-seal themselves. We also revel in lower rolling resistance, lower pressures, more grip and not lugging 400g of extra rubber tube inside our 1,000g rubber tyre.

However, tubeless isn’t without its frustrations.

First off, getting a tyre to pop into the rim bead is often reliant on a quick push of air through the valve. After a couple of goes with a pump and valve, we frequently resort to plan B and plan C – a reservoir of high pressure air and removal of the valve core.

There’s nothing wrong with this, but given the 50/50 nature of ‘normal procedure’/plan B and plan C, it adds faff to the proceedings, especially if you’ve lost your tiny core removal tool and rely on a pair of pliers to get the core out.

Then there’s the ongoing maintenance. By design, the best tubeless sealant is designed to clog small holes – conveniently (or not, as it happens), holes similar in size to the internal passageway air has to move through in a traditional Presta valve port.

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Hence, tubeless valves, regardless of their quality, are prone to clogging.

This leads to painfully slow intentional deflation and re-inflation. Yes, they can be cleaned out or replaced, but who wants that hassle in their life?

The valve core that pops out of the top of the stem is also prone to damage, especially when you lose the little cap in a car park.

Reserve

What makes Reserve’s Fillmore tubeless valves special?

So, why are we excited about the new Fillmore valve from Reserve?

Well, if (and it’s a big if) Reserve’s claims are to be believed, the new valve goes some way to solving a lot of those problems.

Rather than the valve stem holding a valve core within it, the Fillmore’s valve runs all the way through to the bottom of the stem. Pushing down on the top of the valve opens a port at the base of the stem, inside the mountain bike tyre’s air chamber (we’re sure they’ll work with gravel bike tyres too!).

Reserve

This means two things. One – sealant is largely (though we assume not entirely) kept away from the inside of the stem, where it otherwise might clog a smaller port, as when the valve closes, it prevents sealant travelling up the stem. Thus, clogging should be less of a concern.

Two – airflow is less restricted. Air passes through a much broader, more open valve at the base of the stem, rather than having to force its way through a potentially clogged, much smaller port within the stem. As such, airflow is improved, meaning popping tubeless tyres onto a rim should be less fraught with hassle. Obviously, some tyre and rim combos will need some extra grunt, and you may need to make sure your rim taping (that’s another column!) is up to scratch, but we hope it’ll help.

Reserve

What else is there to know?

As the valve system is much more open, you shouldn’t need to remove the core to add sealant, according to Reserve. Just pop your applicator hose over the top and inject sealant.

Reserve

Furthermore, the top of the valve is protected by a broad cap. And this cap itself can be used to adjust air pressure on the trail – dubbed Flow Control: loosen a touch, push down and air escapes, without spraying you with sealant.

The valves are available now, and cost £39.99. Yes, that’s forty quid for a tubeless valve. Like Reserve’s mountain bike wheels, they come with a lifetime warranty, if that makes it a little easier to stomach.

Reserve

Are the valves truly unique?

Off the top of the BikeRadar tech-heads’ heads, we think so – certainly in the cycling space. If there are other variations, let us know in the comments.

There are other ‘posh’ valve systems out there, though. Muc-Off’s V2 Tubeless Valves (£25), among others, have cut-outs at the base of the valve stem to aid airflow around tyre inserts and come with a range of grommets to fit different rim profiles.

Matthew Loveridge / Immediate Media

Milkit’s system (£45) has some of the advantages of the Reserve system. A one-way valve in the base of the stem allows a sealant applicator tube to be poked straight into the tyre’s air chamber to add or remove sealant, and helps reduce sealant from getting into the valve stem.

Reserve

So what do we think?

Well, if Reserve’s promises are to be believed, it seems that the Fillmore could be the valve of choice for those who struggle with the chores of tubeless setup. We have a set here, and will be fitting them to one of our longterm test bikes for a while to see how well they resist clogging. Perhaps now really is the time to stop using Presta valves…

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