Mountain bike inner tubes in 26, 27.5 and 29-inch

What size mountain bike inner tube do you need?

The size of a mountain bike tyre is written in two ways on its sidewall. In inches, it gives the diameter then the width, such as 27.5 x 2.40. In millimetres, according to the ETRTO standard, it gives the width then the inside diameter of the tyre: 559 for 26-inch, 584 for 27.5-inch, also called 650b, and 622 for 29-inch, the same diameter as 700C road wheels. A tube is not designed for a single width but for a range, for example 29 x 1.75-2.50: check that your tyre's width falls within it. Plus tyres, around 2.8 to 3.0 inches, require specific, larger-volume tubes.

Presta, Schrader or Dunlop valve: which one for your mountain bike?

• Presta, marked FV and also called the French valve: slim, it is locked by a small knurled nut before inflating. It is the most widespread on quality mountain bikes and the only one compatible with the narrow valve hole of many rims.
• Schrader, marked AV: the wider car-type valve can be inflated with a service station pump. It is found on many entry-level mountain bikes and kids' bikes.
• Dunlop, marked DV: found mainly on city bikes and some kids' bikes.

The valve must match the rim's valve hole: a valve that is too slim moves about in a hole that is too wide, and one that is too thick will not go through. Its length, often 40 or 48 mm, must protrude far enough from the rim for the pump head to grip. Some Presta valves have a removable core, useful for injecting sealant.

Light, reinforced, puncture-resistant or TPU: which tube for which riding?

On a mountain bike, the most common puncture is the pinch flat: on a rock or root ridden over at low pressure, the tube is trapped between the tyre and the rim, and two small cuts appear side by side, the snakebite. The answer lies in suitable pressure and the thickness of the tube.

• Cross-country: a light tube with thin walls reduces rotating weight and makes the wheel livelier, at the cost of less resistance.
• Trail, enduro and downhill: a reinforced tube, of the Freeride or Downhill type, with thicker walls, resists pinch flats better and allows a lower pressure.
• Leisure and kids' riding: a tube prefilled with anti-puncture sealant plugs small thorn punctures as you ride.
• TPU: these thermoplastic polyurethane tubes weigh much less than a standard tube and fold up very small, ideal as a spare.

Inner tubes and tubeless on the trail

Many mountain bikes now run tubeless, without a tube, with sealant in the tyre. Yet a tube still has its place in your pack: when a cut is too large for the sealant to close, simply remove the tubeless valve, wipe out the sealant, check that no thorn is left stuck in the casing, then fit the tube. Choose it in the right size, with the same valve type, often Presta, and a length sufficient for deep-section rims.

MTB tyres, wheels and repair

Repeated punctures may come from a worn or thin tyre: thicker MTB tyres limit pinch flats, and damaged rim tape on one of your MTB wheels can also puncture the tube. Pumps, patches, tyre levers and sealants are gathered in MTB pumps and repair. For other kinds of riding, see our gravel inner tubes, road inner tubes, BMX inner tubes or all our bike inner tubes.

Which mountain bike inner tube brands to choose?

Continental classifies its MTB tubes by use: the Light range to save weight, the Freeride and Downhill tubes reinforced with extra rubber for downhill riding, the 26-inch Downhill weighing 540 g.

Hutchinson offers the Protect'Air, a tube with an anti-puncture reinforcement and a sealant that plugs small punctures, and the reinforced Koloss for wide tyres from 2.30 to 3.00 inches.

Schwalbe numbers its tubes by diameter, 13 for 26-inch and 19 for 27.5 to 29-inch wheels, and offers an Air Plus version with thicker walls, which holds air longer and resists punctures better.

Slime, a brand specialising in puncture prevention, sells tubes already filled with its anti-puncture sealant, with a Schrader or Presta valve, from 20 to 27.5-inch.

Maxxis distinguishes its tubes by wall thickness, from the light FlyWeight and Ultralight for cross-country to the 1.2 mm Downhill for downhill riding, with Fat/Plus versions for tyres of 2.5 inches and more.

Tubolito makes all its tubes in TPU: the 27.5-inch S-Tubo weighs 45 g, with a Presta valve with a removable core, and packs down very small.

Mountain bike inner tubes on sale

End-of-line tubes move to our MTB wheels and tyres clearance, and new arrivals present the latest models added to the catalogue. Black Friday or the winter sales are a chance to build up a small stock of tubes.

Frequently asked questions

Which inner tube for a 29 x 2.40 MTB tyre?

You need a 29-inch tube, or 622 diameter in ETRTO, whose width range includes 2.40, for example 29 x 2.10-2.50. A 28/29 x 1.75-2.40 tube also fits, at the upper limit of its range. Then check the valve type and length.

Can a tubeless tyre take a spare inner tube?

Yes, it is the most common emergency repair on the trail. Remove the tubeless valve, wipe out the sealant, then run your fingertips around the inside of the tyre to remove the thorn or shard responsible before fitting the tube. The tubeless rim tape can stay in place.

Is a TPU inner tube suitable for mountain biking?

Yes, as long as you choose a model designed for MTB and for the width of your tyre. Lighter and much more compact than a standard tube, it makes an excellent spare.

Why does my mountain bike inner tube keep puncturing?

Two small parallel cuts betray a pinch flat: the pressure is too low for your weight or your terrain, or the tube is too thin. A single hole is more likely to come from a thorn or shard left in the tyre, which you need to find before fitting a new tube. Finally, displaced rim tape can let the end of a spoke pierce the tube on the rim side.

How do you change a mountain bike inner tube on the trail?

Remove the wheel, deflate the tyre completely, then lever one side of the tyre off with two tyre levers. Take out the old tube and check that no foreign body remains in the tyre. Fit the new one, barely inflated, valve first, then push the tyre back onto the rim by hand before inflating.