First and foremost, you want to make sure the tube fits your tyre. To determine the size you need to cheque the side wall markings on your tyre where youll see two numbers separated by an 'X'. The first number refers to the tyres diameter. The second number refers to the tyres width. Select the tube that has the exact same diameter as your tyre. Your tyres width should fall into the range of widths listed on the tube packaging. Standard (also called Schrader) valves are the most common valve type for bicycles. This short, sturdy valve is also used on car tyres and other inflatables. Presta valves are typically found on performance road and mountain bikes. They have built-in valve locks which you twist to open before inflating. An easy way to remember is: 'S' is for Standard (Schrader, Short, Sturdy) and 'P' is for Presta (Performance, Premium). All inflatable tubes are subject to deflation from mis-installation and certain hazards. Finally youll need to choose whether to go with a standard or self sealing tube. Standard tubes are fine for most riding conditions. Self sealing tubes have liquid sealant inside that provides an extra layer of flat protection by sealing holes up to 1/8 of an inch instantly while you ride. It doesnt get much easier than that!