Inner tubes explained
An inner tube is a balloon-like structure that can be inflated and deflated via a valve. Inner tubes are on all bike wheels other than tubeless/tubular options. Upon first inspection it's easy to think that an inner tube will not stretch enough to fill the tyre with air, but they certainly do. When the inner tube is inflated, it fills the gap between the inside of the sidewalls of the rim and the inside of the bike tyre.
What inner tube do I need for my bike?
Inner tubes come in a variety of styles. There are two main things to consider; size and valve type.
Inner tubes are very versatile and cover a variety of widths, but generally only cover one diameter of wheel with the exceptions including some children's bikes. Have a look at your tyre, you will see some numbers either printed or embossed onto the sidewall. These numbers represent the tyre dimensions that determine the inner tube size required. For example, on a road bike tyre you may see the writing 700x23.
A suitable inner tube for this tyre would be the 700x18-23/25 option. This option also covers tyres ranging from 18 to 25mm in width.
Mountain bike tyres are nearly always measured in inches, this actually makes things easier. Think inches for mountain bike and mm for road. The decision making for mountain bike inner tubes is the same principle as for road bikes, the tyre measurements provide you with the details needed for selecting your inner tubes.
Additional markings on the tyre sidewall may include the ISO size. This would look like 23-622 for a 700x23c tyre, and 50-559 for a 26"x1.9" tyre. A full conversion table can be found at the bottom of this page.
The valve is used to inflate/deflate the inner tube. There are two main valve types available, Schrader and Presta.
These are also known as car type valves as they are also seen on motor vehicles. The diameter of the valve is larger than that of a Presta valve, so they will not fit through a Presta specific valve hole found on most road bikes. The most common use of Schrader valves on bicycles is on childrens bikes and mountain bikes.
These are the most common valve type on road bikes and intermediate/advanced level mountain bikes. They are available in different length valves which allow them to be fitted to deep section wheels. To inflate or deflate the inner tube you have to unscrew a small nut on the top of the valve. To inflate you simply attached your pump hose to the valve and insert air. To deflate, you need to press the small nut - this allows air to escape.
The outside of the valve is often threaded to allow a circular nut keep the valve stable in the valve hole of the rim. This helps prevent the valve being twisted/moved when inflating to high pressures.
Some inner tubes have a removable valve core, this means you can add valve extensions for deep section wheels or insert tyre sealant for increased puncture protection.
A less common valve type is a Woods/Dunlop valve. The design is a mixture of Schrader lower valve, and is inflated with a Presta pump adaptor. The Woods valve is gradually disappearing from the market place, Schrader valve tubes are the ideal replacement as the valve stem will fit in an existing valve hole in a rim with ease.
Latex inner tubes explained
Latex inner tubes are an alternative to the standard butyl inner tubes available. Benefits of latex tubes include weight saving due to latex inner tubes being made of a thinner material. This makes the rolling resistance lower too. Another benefit is the ride characteristics, latex is more flexible than butyl so can absorb and react fast to changes in road conditions. This can help in reducing the risk of pinch punctures/snake-bites.
A downside to latex inner tubes is that latex allows air to get through the material easier than butyl does. Latex inner tubes will require a top-up inflation before each ride.
On the sidewall of the tyre you may also find the recommended pressure for tyre inflation. This can be in pounds per square inch (PSI) or BAR (1BAR = 14.5PSI). Weather and riding conditions can effect how much pressure you inflate your tyres too. For road riding in the wet a pressure of 10-15PSI less than normal is recommended to give extra grip, particularly when cornering.
A pressure guage on a pump is very useful, as is a stand alone pressure gauge to check you are adequately inflated.
At Wiggle we only stock high quality inner tubes as the last thing any cyclist wants is to have to stop for a flat tyre. Remember, the tyre is what protects your inner tube. Always ensure your tyres are in good condition and replace them before they are worn out.