Ideal for mountain bikers who already carry a threaded CO₂ inflator and want a quicker trail-side inflation option for higher-volume tyres.
The Muc-Off 25g CO₂ Cartridge - MTB Inflator Refill is the simple fix for riders who want a fast way to get air back into a flat mountain bike tyre without reaching for a mini pump. It’s a 25g threaded CO₂ cartridge intended for MTB use, and it’s designed to work with the Muc-Off CO2 Inflator Kit for quick inflation on the trail.
For mountain bike tyres, cartridge size matters. A 25g cartridge carries a larger gas charge than the smaller road-style options, which makes more sense for higher-volume MTB tyres when you need a rapid refill after a puncture. Muc-Off rates it to inflate a tyre up to 30 psi from flat, which lines up with what most trail and all-mountain riders are actually aiming for rather than road-bike pressures.
The main reason to choose this refill is practicality: it’s compact, quick to use, and easy to stash as part of a puncture kit. It also uses the common threaded cartridge format, so if you already have a compatible threaded inflator head, it’s a straightforward spare to carry. As with any CO₂ setup, it’s best treated as a fast ride-saving option rather than your only inflation plan for long remote rides, and it pays to top the tyre up properly with regular air once you’re home.
25g MTB-focused cartridge
The 25g charge is better suited to mountain bike tyre volumes than smaller road cartridges, making it the more practical pick for trail use.
Fast inflation from flat
Designed for quick puncture stops, with stated inflation of up to 30 psi from flat for MTB tyres.
Threaded cartridge format
Uses a threaded design that works with the Muc-Off CO₂ inflator system and many other threaded inflator heads.
Built for puncture kits
Small and easy to pack, so it fits neatly into a saddle bag, frame storage setup or riding pack.
No hand pumping required
A handy option when you want to get rolling again quickly without the effort and time of a mini pump.
Best matched to MTB pressures
Well suited to the lower pressures commonly used on mountain bikes, where speed matters more than chasing very high PSI.
General
Dimensions & weight
Compatibility
Features
Great for
Maybe not for
This is a 25g threaded CO₂ cartridge for MTB use. It is designed to work with the Muc-Off CO2 Inflator Kit, and Muc-Off states compatibility with most threaded 16g and 25g CO₂ cartridge systems. Always check that your inflator head suits threaded cartridges before buying.
vs Lezyne 25G CO2 Cartridge
A direct alternative in the same 25g threaded CO₂ cartridge category, aimed at high-volume mountain bike tyres and use with threaded Lezyne inflators.
vs Topeak 25G Threaded CO2 Cartridge
Another 25g threaded refill option, intended for Topeak’s AirBooster, HybridRocket and related CO₂ inflators.
vs Peaty's Holeshot CO2 Tyre Inflator Kit MTB (25g)
A more premium complete inflator kit rather than a refill-only product, built around 25g MTB cartridges and a compact inflator head.
Carry the right size for MTB tyres
For mountain bike use, a 25g cartridge is the safer bet over a smaller road-size option because higher-volume tyres need a bigger gas charge to reach rideable pressure quickly.
Check for threaded compatibility first
Before buying spares, make sure your inflator head accepts threaded CO₂ cartridges. This refill is intended for that common threaded standard, not every inflator style on the market.
CO₂ is brilliant for speed, not endless backup
This kind of cartridge is ideal for fast puncture stops, but it is still a single-use item. For bigger days out, many riders still carry a mini pump as a backup once the cartridge is gone.
Expect the cartridge to get very cold in use
CO₂ systems chill quickly when discharging gas, so use a proper sleeve or keep your hands clear of bare metal while inflating.
Muc-Off is a British bike care and maintenance brand that began in 1991, when Rex and Marilyn Trimnell started X-Lite UK. After developing the world’s first twin crown bicycle fork, Rex created the pink bike cleaner that became the foundation of the Muc-Off brand.
The company has since expanded well beyond cleaners into a broader range of cycling maintenance, tubeless, inflation and performance products. Muc-Off is based in the UK and has built a strong presence across both everyday riding and top-level racing.
