Flat Fixing, Part 1 of 3: Know Your Tube
In just 3 short blog posts, we’re gonna show you how to change a flat tire! It’s not that difficult, and it is an invaluable tool for every cyclist to know.
First things first, you need to have a spare tube with you when you ride. And you’ll want the right size tube!
The very first blog post of our Service Series was about learning the proper inflation of your tube and tire, also known as PSI. The same place where you find your PSI, on the side of the tire, is where you find the size of your tire and tube.
The sizes of tubes and tires is waaaay more complicated than it should be. Some are measured in British, some in Imperial (US). There are literally dozens of tube sizes that we stock in the shop although some are certainly more common than others. But none of this matters if you can just read the size off the side of the tire!
There will be 2 numbers linked by an “X”. That’s all you need.
So, the tire on the left is 700 millimeters in diameter and 32mm wide and is referred to as a “700 by 32.” (You can ignore the “c,” it’s a holdover from an old French measurement system and isn’t used at all anymore. It doesn’t mean centimeters. Yeah, tubes and tires are unecessarily complex.)
The tire on the right is 26 inches in diameter and 2.1in wide and is referred to as a “26 by 2.1.”
Pro tip: If you don’t have your bike with you at the shop and don’t want to deal with this nomenclature, you can always just take a pic of the numbers on your phone and show one of us.
Next up, you’ll need to know what kind of valve you have.
The tube on the left has a Schrader valve, or SV. The tube on the right has a Presta valve, or PV.
So now you can walk confidently into the shop and say, “I need a 26x2.1 SV tube!” or “I need a 700x25 PV tube!”
If you’d like to take the next step and stare down those shelves of tubes and select your own, just remember that tube widths are sold in ranges. Basically the tube for your 26x2.1 tire will be 26x1.9-2.125. All you need to make sure is that your diameter (ie, the number before the “X”) matches and that your width (ie, the number after the “X”) fits within the range of numbers on the tube box.
In the photo above, we’ve got a 700x37 tire with a Presta valve. The correct tube is 700x35-43 PV.
One last thing to remember, if you have a Presta valve, there are also different lengths. It’s more than likely that if you are riding a wheel that requires a long Presta valve, you will know that about it, since it’s kind of a high-end thing. But when in doubt, just ask. We are happy to help you figure it out!
Tubes do range in price depending on size, but most are in the $10 range (super skinny and super fat ones tend to cost more).
And if any of this sounds overwhelming, don’t stress. We got you! We can show you how to read the size off your bike or, if you are on a need-to-know basis with bike maintenance, just show us the bike or a photo of the tire and we will grab the proper one for you.