Which Inner tubes?
When thinking about which inner tubes to buy, you need to know a couple of things. First it’s size and then which valve it also has.
Size is usually written on the wall of the tyre. As a general rule of thumb mountain bike tyres are usually written in inches, whereas road bike tyres will be found in mm.
- Mountain bike sizes
26”(some hybrid and city bikes too)
- Road tyres
- Folding and kids bike
Some have even smaller tubes
The first number (ones above) show the diameter and the number that follows the Times (x) is the width. When choosing which inner tube, the box will state a range of widths it covers, for example your tyre states 700 x 32, so you can choose an inner tube which covers 700 x 23/32 or 700 x 32/45.
To c or not to c
You may be wondering what the little ‘c’ stands for after the numbers. This is usually found on 700’s. Form the reading i’ve done, i’ve concluded that it means nothing. Don’t get me wrong at one point in time it was a french system that referred to the width of the rim. This ranged a,b,c and d. The letter codes no longer correspond to the tyre width, since narrow tyres are often made for rim sizes that originally took wide tyres; for example, 700 C was originally a wide size, but now is available in very narrow widths. You’ll probably come across 650b. This size is making a comeback on mountain bikes and refers to 27.5”, again the b is the old french system that refers to the bead width, b being pretty wide.
As for the valves, the short, fat valve is called a Schrader valve and is used on mountain bikes and the pointy one is called a Presta valve. The Presta valve is used for road bikes where a higher pressure is needed. Another thing to think about is the length of the valve. If you have deeper rims a longer valve will be needed so you can easily attach a pump. These come in 42mm or 62mm and extensions are available if you run rims that are over 50mm. The Dunlop valve, (also called a Woods valve or an English valve) is a type of pneumatic valve stem in use in some countries. To pump these inner tubes up a screw on adapter for a presta valve works best, although some push on pumps may work.
Why all those number?
As you see from the picture some tyres have a lot of numbers on them, this can cause confusion. Which size inner tube do I buy? 32-622, 28 x 1.25 or 700 x 32c ?? If you find any combination of these numbers on an inner tube box, then it’ll be the right size.
You don’t have to read anymore if you’re quite confident you’ll be able to work out which size you’ll need, and that’s all you need to know. The different numbers are simply just different measuring systems, one being inch based systems and the other being metric based systems.