Tube
A bicycle tube is basically a doughnut-shaped balloon made of butyl rubber with a valve attached so you can inflate it. Being made of rubber, a tube has no rigid structure. Once inserted inside the tyre the tube will expand to 2-3 times its original size filling out the tyre until it fits snugly up against the inside wall of the tyre. Tubes do not have a pressure rating; inflation pressure is relevant to the tyre and is printed on the side wall of the tyre. There are different types of tubes manufactured to varying quality standards.
High quality tubes are thinner and lighter than standard tubes. Thinner tubes do not increase the risk of punctures as you might think. The purpose of using a thinner tubes is to allow the tyre to give and flex under pressure as it was designed to do without the tube hindering movement. This is very important if you are running high quality race tyres. Companies like Continental, Michelin and Maxxis manufacture tubes that are specifically designed to match the performance of their tyres. If you are investing in good quality tyres for your bike but are still using cheap tubes… it would be a good idea to pull those crappy tubes out and replace them with good quality ones. High quality, light weight tubes cost between $11 and $15 dollars and are without doubt one of the best value performance upgrades you will ever make!
If you live out back and thorns are an issue consider changing over to Flat Fighter tubes. These tubes are available for BMX bikes and Mountain Bikes. Flat Fighter (thorn proof) tubes are 600% thicker than a standard tube and are filled with a special sealant that fixes punctures from the inside.
The two most common tube valves are Presta and Schrader (or American Valve). Schrader valves are the same as car tyre valves and are the most common valve type. Presta or French Valves are thinner; they were designed to suit narrower rims where the structural reliability of the rim would be impaired if the Schrader value was used. Typically, Presta valves are used for road bikes, hybrid bikes and off road mountain bikes.
