Tubeless Valves

Tubeless Valves can be a weak point in a tubeless set-up, how are brands dealing with it?

If you’re a tubeless user you’ll be familiar with one of its weaknesses; the Presta valve. Why is the Presta valve a problem? Take a look at one, particularly the removable inner part; it’s tiny! Being so small – the main body is only 6mm in diameter – leads to two problems that the original designers couldn’t have foreseen when they invented it over 100 years ago.

Problem 1 – Air-Flow

The first issue comes when you try and inflate your tyre. Tubeless setups need a big rush of air to push the tyre up against the rim walls, creating a seal. Without this initial burst, the air just leaks out around the tyre’s edges. However, because Presta valves internals are so narrow, you often don’t get that big rush that you need. You can get around this restriction by using a high-pressure air supply, or removing the inner-valve. While this isn’t an issue if you’re at home, it can be a real pain if you’re out on a ride and need to get a tyre back on.

Problem 2 – Sealant

The other problem you’ll come across, related to Presta valves is sealant. Sealant is used in tubeless tyres to seal punctures. It does this by suspending fibres/particles in a solution. When you puncture the fibres are carried by the solution to the hole, as the air inside rushes out. The sealant is pushed through the hole, where the fibres begin to block the puncture and the liquid sprays your buddy behind you!

That is fine when you have a puncture, but as far as your sealant is concerned the valve is also a kind of puncture. It will build up inside blocking the internals until eventually you have to replace them. This will take a while and in the meantime can be really annoying when you are trying to add or remove air; usually at the start of a ‘cross race!

76 Projects Hi Flow

So various brands have taken a look at the Presta valva to see how they could improve its tubeless performance. I first came across an alternative with 76 Poject’s Hi Flow valves. These were a revelation with how much easier they were to live with. Their design has what they call a transfer chamber at the top of the valve stem. Inside here is a short, hollow piston that allows air to flow through it. The chamber is much wider than a standard Presta stem, allowing air to flow freely. Air pressure from below pushes against the piston, sealing the valve. Meanwhile an external brass lock-nut allows you to release air, or lock it off.

I’ve used them with on and off-road tubeless set-ups and they often allow me to seat tyres first time with just a track-pump. I haven’t had any problems with the valves becoming fouled with sealant, yet. If they do however, they can be dismantled and de-gunked, which is a bonus.

Fillmore Valve

Recently I took delivery of a set of Fillmore Valves, these are made by Reserve Wheels, who make carbon wheels. Their tubeless valve uses a long stainless-steel piston that runs the full length of the valve stem. It’s secured at the bottom end, but is free to move up and down. When you introduce some air pressure, this pushes it against the bottom opening and seals the stem, simple.

The piston’s top end is finished off with a screw thread. This allows a metal top-cap to be screwed on, which serves two purposes. Firstly it allows you to lock off the piston and stop it releasing air. Secondly, if you unscrew it you can use it to regulate the internal air pressure. The more you unscrew it, the more air is released when you press it. You can do the same by just pressing the threaded end of the piston, but it’s less controllable. As with 76 Project’s valve, you can easily disassemble the Fillmore to clean it.

Stan’s Tubeless Exo-Core Valves

Stan’s have been around in the tubeless world for a long time, for many riders they’re the first brand they come across. They make everything you need to go tubeless; wheels, rim-tape, sealant and valves. Their Exo-Core valves are their Presta-busting option for making tubeless easier.

The Exo-Core has it’s moving parts situated on the top half of the valve’s stem. Here you find a screw-on housing with a brass core inside. This allows air and sealant in and out and can be removed completely if you want to pour sealant straight in, or are having problems getting a tyre to seat. The top cap is a press-on affair and is there just to protect the core’s top and keep dirt out. The Exo-Core will come out in summer ’24.

Muc-Off Big Bore Tubeless Valves

Next we have Muc-Off’s Big Bore Tubeless Valves, which look like they could have the best air-flow. This isn’t based on any actual experience with using them as they are yet to be released. Looking at the cut-aways, the internals look simple and uncluttered, which should mean lots of air-flow.

The design again keeps the moving parts at the top end of the stem, leaving the bottom free for rapid air movement. The top of the valve has a machined aluminium housing, inside of which is a stainless-steel, coreless ball-valve. Twisting the lever on the outside opens and closes the valve, the core of which is the same diameter as the stem. To release air looks to be a simple matter of cracking the valve, open it too far though and you could dump all of it in one go!

Not one but three!

Unusually Muc-Off will release three versions of the valve: Big Bore Lite, Big Bore Hybrid, and Big Bore Ludicrous. The Big Bore Lite has a 3.3mm internal diameter valve head. This Muc-Off say gives 230% greater airflow than a standard Presta valve. The stem will work with Presta style pumps and rim holes.

Next is Big Bore Hybrid, this has a Presta style valve-stem, but with a wider valve head offering a 5.7mm internal diameter. This gives 254% more airflow than Presta and allows you to use Schrader compatible pumps. The stem will still fit through a Presta-sized rim hole however.

If you do have Schrader-sized holes in your rims, then you can use the Big Bore Ludicrous. Muc-Off call this “big bore munitions for your bike!” The valve head and stem both have a 5.7mm internal bore. This means you get 264% greater air-flow compared to a standard Presta valve.

e13 Quick Fill Presta Tubeless Valve

Lastly we have e13’s Quick Fill Presta Tubeless Valve. This is a little different from the previous valves as it’s not trying to solve the Presta issue. Instead e13 have focused on getting sealant in and out of the tyre, bypassing the valve completely. Their valve top simply unscrews from the stem, exposing a wide bore opening. You simply fill your tyre with sealant and then screw the top back on.

By removing the Presta valve from coming into contact with sealant, this should keep it cleaner a little longer. While it won’t remain completely free of sealant, it does make maintaining your tyre’s levels a lot easier.

So there we are, the Presta valve is dead! Well not completely, while it does have its drawbacks it does have one advantage over these new versions; it’s cheap! You can buy a pair of standard Presta tubeless valves for around a fiver. These new valves will cost more than double that; much more than that in some cases. The advantages are that they offer a much easier tubeless set-up; I swear a lot less since I stared using them! They can also be dismantled and cleaned, something you can’t do with a Presta valve. So, take a look and see if you’re life could be that much sweeter with an alternative valve.