What Does 700c Mean On A Bike? (Quick Answer)

Quick Answer:

700c is the size of your bike tire, according to the ‘French system’. The “700” number is the stated diameter of the bicycle tire in millimeters. “c” is the width code of the tire (as you would see if you looked at your bike from behind or in front). C refers to the old French system which classified tire widths from “a” (the narrowest) to “d” (the widest). So, a “c” tire was almost as wide as these would get.

How to find bicycle tire size

You will find the tire size of your bike located on the sidewall of your tires (just above the surface where the brake pads touch). If you stand to one side of your bicycle so that the tires are seen as an ‘O’ shape. The sidewall will be the part of the bike tire that you can now see. It will be fairly smooth, without the knobbles and grips on the tire surface where it touches the road.

Look along the tire sidewall and you will see a variety of numbers and words in the rubber. You will see “700c” and you may also see something like “700 x 38c” (or a number close to 38). This is your tire size. The “700” is the tire diameter and the “38c” is the tire width.

What size bicycle tire do I need?

In simple terms, you need a new tire that is “700x38c” (or whatever the “38” number is on your current tire). Tires that are just about ‘close enough’ sadly won’t be sufficiently close enough and you will undoubtedly get issues, for example, punctures.

You do however have a choice in terms of (a) the amount of ‘tread’ i.e. the knobbliness of the tires, and (b) the brand that you choose.

I’ve been using a range of Continental tires recently and they’ve been very good quality. Smooth and fast-rolling and, touch wood(!), I’m yet to get a puncture in any of them despite putting a few miles on the clock. I’d recommend these Gatorskin tires from Continental which are light, fast and have very good puncture resistance. They come in a range of width sizes, including 23mm, 25mm, 28mm, and 32mm, so pick the one that matches your existing tire.

What bike inner tubes should I buy?

When you’re choosing an inner tube for your tire, you need to pick a tube with a diameter that matches the one shown on your tire (in our case, this is “700”) and a range of widths that includes the diameter you need ( e.g. if your tire is “700x38c” then it’s the “38” that’s relevant here).

The width of an inner tube really depends on how much they’re inflated. So you’ll see them labeled with the diameter and a width range, e.g. “700×32-42”. That means that they’ll suit tires that are in the range of 700×32 up to 700×42.

This is a great example from Continental. It comes with a Presta valve and there are three different width options available:

  • 20-25mm
  • 25-32mm
  • 32-42mm

It’s worth bearing in mind that, if your bike pump has a standard car tire valve (called a Schrader valve) then you’ll need to get an adaptor, like this one, to allow it to inflate Presta valves.

Unfortunately, there’s no getting round this as Presta valves are much slimmer than Schrader. Have a look at the pictures on the Amazon page and you’ll see how easy the adaptors are to fit and use.

How do I replace bike tire and inner tube?

Getting a flat tire on your bike, while very annoying, is easy to deal with if you’re prepared and have the right kit. Make sure you carry a spare tube (of the correct size), a repair kit, tire levers, and a good quality pump. Then follow these simple instructions to get back on the road fast.

Here are the basic steps to fixing a flat:

  1. Remove the bike wheel
  2. Remove the tube
  3. Find the cause of the flat
  4. Repair or replace the tube
  5. Reinstall the bike wheel

For an easy how-to guide, have a quick watch of this video.

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