Tire punctures are one of the most common problems faced by avid cyclists. Being able to repair a puncture on your own is a very handy skill to have if you’re planning to venture further than the corner store on your bike.
First, you need to know how to choose the right inner tube.
To choose the right inner tube for your bike, you must determine three things: the size of your wheel, the width of your tire at the type of valve that is compatible with your wheel rims.
The tire is the surface that you are riding on − the rubber structure that absorbs the shocks and vibrations of the road. The inner tube is the tube inside the tire that holds the air.
Look closely at the sidewall of your tire and you should find a series of numbers that looks like 700 x 35, 26 x 1.75, 29 x 3. The first number indicates the size of the wheel.
A bicycle’s wheel size is expressed in inches or centimetres, generally according to the type of bike. Wheel sizes for road bikes or hybrid bikes are usually metric. 700c is the most common size, which can sometimes be expressed as 28 inches. However, 650b wheels (which are slightly smaller) are becoming more prevalent.
What does 700c or 650b mean? They are the two most common standard sizes in the world of cycling. The number is an approximate measure of the diameter of the wheel in millimetres, including the tire. The letter is a historical indication that no longer has any real meaning.
For mountain bikes, some hybrid bikes and kids’ bikes, the diameter of the wheel is generally expressed in inches. 12, 16, 20 and 24 are common kids’ sizes, while 26, 27.5 and 29 are common sizes for adults' mountain bikes.
In all cases, the measurements represent the approximate diameter of the wheel including the tire.
Are you confused by the various wheel sizes for adult bikes? Here is a chart that shows the equivalencies. ERTRO is the the standardized measurement of a wheel’s diameter.
The same basic logic applies for the width of the tires. If the size of your wheel is metric, the width should be as well.
You will find the width of your tire in the second digit marked on the sidewall of the tire. So, a tire marked 700 x 35 has an approximate width of 35 mm and a tire marked 27.5 x 2.3 has an approximate width of 2.3 inches.
There are two basic types of valves for bikes. Schrader valves, identical to the valves found on car tires, and Presta valves, which have a smaller diameter.
Schrader valves have the benefit of being compatible with gas station compressors. Luckily, there are adapters to make Presta valves compatible as well.
Don’t forget! A Schrader valve will never be compatible with a rim designed for a Presta valve because the hole on the rim will be too small. The inverse, however, is possible.
Presta valves must be loosened before filling with air.
Once you know the type of valve, the size of the wheel and the width of the tire, you are ready to choose the right inner tube. This information will be clearly marked on the product’s packaging.
***Last tip: When you're stuck on the side of the road, far from home, with the wrong size inner tube...
If you have the right type of valve, you should be able to use an inner tube that is slightly larger than one that fits all the parameters of your wheel and your tire. This will allow you to get yourself back home safely. However, once you make it home, be sure to change your inner tube for one that is the correct size!