What size bike tubes do I need?

Lester Perry | Thu 4th Jun 2020 11:59

You'd be forgiven for thinking that a bike tube is just a bike tube. However, they come in a range of sizes for different wheels and riding types. In this guide we'll explain how to choose the right size and some of the key differences to watch out for.

Whether you’re shopping for spare tubes or replacing a punctured one, you’ll need the correct inner tubes for your tyres. They come in a wide range of wheel diameters, widths, valve types and materials. With so much choice how do you decide which one is right for your bike?

Tube Sizing

Start by looking at the side of your bike tyre. There should be some numbers printed or embossed on the side. These may be marked in inches or millimetres depending on the brand and application, for example below.

MTB tyre sizing indicated on the sidewall - 29x2.60" tyre
Road bike tyre sizing indicated on the sidewall - 700x25 tyre

In the first instance, the “29” represents the diameter of the wheel and the “2.6” denotes the tyre width. Tubes are available to fit all modern dimensions, and generally they fit a range of tyre widths. For example, a tube may be marked as “27.5 x 2.3-2.5” showing it is for a 27.5” diameter wheel and will cover a tyre width from 2.3-2.5 inch.

A Box of 26" diameter tubes for tyres 1.95" to 2.125" wide. 48mm long Presta valves.

It’s best to use a tube that suits your tyre size. If the tube is too small, it will expand outside its intended range once inflated, becoming thin and more prone to punctures. If the tube is too large, it will bunch up inside the tyre, increasing the chance of punctures and potentially creating rolling inconsistencies tyre.

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Valve Type

Once you have the right tube you’ll need the correct valve for your rim. Modern bikes are usually fitted with Schrader valves (also used on car tyres) or Presta (generally used for high-pressure bike tyres and also known as “French Valves”). Presta valves are available in a range of lengths according to rim depth. If you’re running deep-section rims you’ll need to carry a spare tube with a valve that’s the right length. Ideally it will protrude at least 1 cm from the rim so that your pump-head will fit over it. A variety of valve extenders are available to help with this if needed. Some simply screw over your existing valve, while others require the removal of the valve core, so it’s important to purchase the correct extender for your valve.

Presta Valve / French Valve
Schrader Valve
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Materials

Most tubes are made of butyl rubber, which is nothing fancy, but it does the job. If you’re concerned about weight, it might be worth upgrading to a Latex tube. Latex’s lighter weight and increased suppleness offer faster rolling and better traction, making it the choice of many racers. Modern tube-manufacturing techniques also allow the use of leading-edge materials such as thermoplastics. These are super-lightweight and offer increased puncture resistance over butyl.

A butyl tube and a Tubolito Ultra Light tube made from modern thermoplastic.

Tubeless

Depending on what rims and tyres your bike has, a tubeless set-up may be possible. This removes the weight of the tube, increases the road/trail feel, allows you to run lower pressures, increases traction and lowers the likelihood of punctures. The average tubeless set-up involves replacing your protective rim strip with a tubeless-specific type (although some rims won’t require this step), installing a compatible valve and tubeless-ready tyre, and finally adding some sealant. The sealant helps seal the system, and then while you’re riding it helps seal any punctures.

Tubeless sealant and a tubeless valve with the core removed.
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