Inner tubes are normally made of butyl rubber or Latex, they sit inside your tyre and are inflated with pump, they sometimes puncture but are easily replaced. Inner tubes are simple but essential – unless you’re riding with tubeless tyres, you’ll always need an inner tube. Carrying spares is always a good idea, even if you are running tubeless, as a large slash or hole will not seal easily.
There are many different types of inner tube available so it is important that you get the right tube for your bike, and to suit the riding that you are doing.
The tube needs to fit your tyre to avoid overstretching or pinching, both of which are likely to cause punctures, and the tube material needs to be appropriate for your style of riding. For competitive road racing or time trial you might want to consider the weight, to gain a performance advantage, whilst for downhill mountain biking puncture protection is likely to be your highest priority.
When it comes to replacing your inner tube, how do you know which size you need for your bike? There are a myriad of wheel sizes for road, MTB, touring and children’s bikes. MTB wheels, in particular, can be further categorised by 26 inches, 27.5 inches and 29 inches. To confuse matters further all tyres use the European Tyre and Rim Technical Organisation (ETRTO) system, so for a road, it would display 622 x nn with the nn value indicating the tyre width which is the same as 700 x nn. This value is displayed on the tyre wall, the first place to check for your tyre size. Once you know this you can then determine the size of tube you need. Some tubes will display 700 x 20-28c so this will fit tyres with a width between 20 and 28c.
You must make sure you replace your inner tubes with a tube that is the right size according to the diameter and width for your tyre. The size is almost always written somewhere on the sidewall of the tyre. Inner tubes typically state a wheel diameter and width range for which they will work, e.g. 26 x 1.95-2.125", indicating that the tube is intended to fit a 26 inch tyre with a width of between 1.95 inches and 2.125 inches.
Another example might be 700 x 18-23c, which seems less obvious but 700c is the diameter of Road, Cyclocross, Adventure Road and Hybrid bike wheels, and the numbers relate to the width in millimetres, so 18mm-23mm wide. Many Road tyres are now 25mm and Cyclocross, Touring and Hybrid bike wheels may have tyres fitted that are up to 36mm so make sure you carry the appropriate width tube.
On bikes, Schrader valves tend to be used on lower pressure tyres, such as children's bikes and mountain bikes. These are the same valves used on all automotive tyres and are often referred to as ‘car type’ valves. Schrader valves have a core that is sprung loaded, and the central pin can be depressed with a narrow object to release air from the tube. The spring mechanism keeps the valve closed.
If you plan fast downhill riding, there are tubes designed for slamming into rocks and obstacles, such as the Onza Downhill inner tubes.
Presta valves are valves which have a slimmer stem, sometimes threaded to accept a locking ring, which holds it tight in the rim drilling. They are usually found on higher pressure tubes such as on a road bike. To inflate or deflate via Presta Valve, the top section must be unscrewed, allowing the core of the valve to be free to move. This will allow the valve to open and close. In this high pressure valve, it is the air pressure that shuts the valve and then the closing of the top section that keeps it shut.
The Dunlop valve, also known as a Woods is a variation of pneumatic valve that is rarely used on modern bikes. However they were once popular. They look like a cross between the two valves, with a wider lower section, like the Schrader, then a collar and a narrow top section, like the Presta. As the rim drilling is the same for both Woods and Schrader, it is easy to replace the older tubes with the more modern variety.
Presta inner tubes are available in different valve lengths to be appropriate for use in deep section rim profiles. If you have deep section rims, make sure the valve is long enough to extend through the rim hole, and still leave enough valve stem showing to fit the pump onto. Valve extenders can be purchased to make a shorter valve fit, and are also a good idea to carry as an emergency spare if you know your tubes require it.
INNER TUBE VALVES
Presta valves vary in length
depending on your rims depth
Butyl rubber is the industry standard for common replacement inner tubes, offering a relatively cheap and readily available replacement product. Butyl is strong and resistant, and there are lightweight versions for those looking for weight savings - the Specialized Turbo range and Continental Supersonic tubes are popular versions.
Latex rubber tubes offer slightly enhanced handling characteristics - because latex rubber is slightly more flexible than traditional butyl rubber, the tubes adapt quickly to the tyres changing shape while cornering and on impacts. Latex tubes generally have a thinner wall, offering obvious weight savings. Latex tubes have also been proven in multiple tests to have lower rolling resistance, making them faster.
Despite the advantages, it is important to recognise the flaws of Latex. Latex rubber reacts badly to contact with some oils and greases so must be handled carefully in the workshop. Also Latex is more gas permeable than butyl rubber and, as a result, latex rubber tubes do not hold the air as long as butyl based tubes and require more frequent inflation, as well as being fairly fragile and easy to tear when inserting. Despite their flaws, latex tubes are a faster and lighter, so worth the investment if you're aiming to be competitive.
Sealant is suitable for use with inner tubes with removal cores. By pouring the sealant into the inner tube it is able to quickly seal small holes by drying and forming a clot over the hole when it comes into contact with the air. It will easily seal the type of holes that you may get from road debris or thorns. Puncture protection is incredibly useful for commuting and mountain biking.
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