Valves

Tubeless Valve Guide

Tubeless valves are small parts that cause disproportionate frustration when they don't work right. A good valve with a clean seal against the rim tape is essential for a reliable tubeless setup. A bad one leaks air around the base, clogs with sealant, or won't accept a pump head cleanly.

Valve Length

Valve length needs to clear the rim depth plus enough extra for a pump head to lock on — typically 5-10mm of valve protruding above the rim. Standard MTB rims need 35-44mm valves. Deep-section or carbon rims may need 60mm+. Too short and the pump head won't engage. Too long is fine functionally but looks messy and adds minimal weight. When in doubt, go longer — you can always add a valve nut to take up slack.

Valve Base Diameter

The rubber grommet at the valve base seals against the rim tape. Most Presta tubeless valves have a standard base that fits rim holes drilled for Presta (approximately 6.5mm). Some rims have wider valve holes — you'll need a valve with a larger base grommet or a shim. Stan's, Muc-Off, WTB and most aftermarket valves include removable rubber grommets in two sizes to cover the common rim hole diameters.

Removable Valve Cores

Every tubeless valve should have a removable core — this lets you inject sealant through the valve with a syringe rather than breaking the tyre bead. Removable cores also make cleaning easier when sealant clogs the valve (which it will, eventually). If your valve core is stuck, a valve core removal tool (a few quid from any bike shop) grips the core and unscrews it. Carry a spare core on rides — if a clog won't clear, swapping the core is faster than fighting with it.

Material

Alloy valves (anodised aluminium) are lighter and come in colours to match your build. Brass valves are heavier but more durable — they don't cross-thread as easily and the sealant doesn't corrode them. For practical purposes, either works fine. The aesthetic crowd runs alloy. The pragmatic crowd runs brass.