Muc-Off Big Bore Lite Tubeless Valves

Muc-Off's Big Bore Lite Tubeless Valves are nicely engineered and more or less immune to getting gummed up by sealant. The airflow through them is much higher than cored Presta valves, which can also make sealing tubeless tyres less of a chore, depending on how you do it. They're expensive, but they're really good.

First off: how are they different? Well, the Presta valve we're probably all familiar with has a removable core, which screws into the valve stem. You can lock this with a small nut on a threaded rod, and when open the valve can be depressed to allow air into the tyre. It's a great system that for the most part works flawlessly. Or it did, until tubeless.

Tubeless tyres introduce two new things for the valve to cope with. Firstly, you need to actually seal the tyre against the rim. This requires a blast of air from a compressor or a tyre booster, or some very quick work on the pump. The problem is that a Presta valve just isn't designed to handle that level of airflow. Normally, you have to remove the core to seal the tyre, then deflate it and put the valve back in before blowing it up again.

The second issue is sealant: this is literally designed to gum things up and there's nothing it likes to gum up better than the delicate workings of a Presta valve. Cored valves have a limited lifespan when you're running tubeless. Muc-Off sells them in packs of 10 for this very reason.

Having a ball

The Big Bore Lite Tubeless Valves (the 'Lite' just means they're a bit more slender than the standard ones) eliminates the core, and both problems, at a stroke. Instead of a core it uses a ball valve: a ball with a hole through the centre that can turn to either allow air through or block it. It's a simple, durable and effective valve; you've probably got half a dozen in your house, in the plumbing and the gas.

The ball valve in these units is stainless steel and actuated by a twisting alloy lever on the side: parallel is closed, perpendicular is open. The valve screws onto an alloy stem, the base of which has some horizontal air channels in it to stop a tyre liner blocking everything up.

Three different rubber inserts are included for various rim shapes. Installing them was no more difficult than any other valve, really – you have to remove the valve head to fit the stem through the rim, but it's hardly a chore.

Muc-Off says that the miniaturised version in the Big Bore Lite valves has an airflow that's up to 230% higher than a standard cored valve. So that might mean that you'll be able to get your tyres seated without removing the valve section. It won't mean that for me – I use a Schwalbe Air Booster that's designed to screw onto the valve stem without the core, and there was no way to seal it with the valve in place. If Muc-Off added a bit of valve-stem-size thread above the valve as well – or included a thread adapter – it would work with a wider range of tubeless boosters out of the box.

I did try using a friend's compressor, and the throughput is impressive. It's still not as high as it is without the valve, though, and for me the minor faff of removing and refitting the valve – even easier in this case because the valve is much bigger – is worth it for dependable tubeless sealing. Your mileage may vary there.

On the second point there's no doubt that the ball valve in these valves is much, much less prone to clogging than a standard core. The main reason for this is that there's just loads more space, but there are also other factors. Ball valves are all smooth faces, whereas a Presta core has a threaded rod down the middle with loads of crevices for sealant to catch and congeal. Also, the actual valve in a Presta core is usually rubber, and there's nothing that tube sealant likes to stick to more – that's its job, after all. The stainless steel of the ball valve is much less attractive, and the action of opening and closing the valve will shear off any sealant that has managed to stick.

I've had no more air loss from my tubeless tyres during testing than I'd normally expect, so the valves have sealed well against the rim, and the ball valve is airtight when closed. If you're adjusting your tyre pressure on the fly then it's even easier than with a cored valve – you get a bigger thing to tweak, and you can open the valve just a little bit to leak out a few psi.

Value & conclusion

At 40 quid a pair, these are up against products like the Reserve Fillmore valves and the 76 Projects Hi Flow valves, both of which use different internals to a standard core. The 76 Projects are all a bit cheaper (if you can actually find the ones you want), but of the Reserve ones, only the 50mm are cheaper; the 70mm are the same price, and the 90mm are £44.99 (all sizes of the Muc-Offs – 30, 35, 45 and 60mm – are £40).

I really like the use of a ball valve here. I think it's the neatest engineering solution to the problems of airflow and clogging thus far, and I'd recommend them, even though they're expensive.

Verdict

Great engineering solution to tubeless problems built into a quality valve