Here’s the quick answer:
700x25c is the dimensions of your bicycle tire, using the ‘French system’.
Let’s break it down. 700 is the nominal diameter of the bike tire, sized using millimeters.
The next number, 25, is just the width of the tire (this is also measured using millimeters).
The final c refers to the width code of the bike tire (the width being what you’d see of the tire by looking at the bike when you’re standing behind it or in front of it). Thankfully we can safely ignore the “c” bit as these days it’s fairly obsolete, but it used to be a key part of the former French system of classifying tires that designated widths from the narrowest, which was “a”, all the way to the widest, which was “d”. So a “c” bike tire was one that was almost the biggest width for these tires.
How to find bicycle tire size
The bike tire sizing will be on the sidewall of your tires.
The sidewall is the strip of rubber that is just above the metal surface of the wheel’s rim, where the brake pads touch the wheel. If you’re unsure which bit is the sidewall, then stand on the side of your bike, so that the tires can be seen as an ‘O’ shape and the spokes are on view. The sidewall of the tire is the rubber bit that you can now see going round the rim. It will be much smoother, without any of the lumps and bumps that you get on the surface where it meets the surface of the road.
Inspect the tire sidewall closely and you’ll see there are numbers and probably some words set into or printed on the rubber. These will most likely include the brand of the tire (for example, Continental) and also include “700x25c”, which is the size of your tire.
So, just to sum up, “700” is your tire’s diameter and “25c” is your tire’s width.
Let’s carry on and look at my recommended 700x25c tires and tubes to fit your bike.
What size bicycle tire do I need?
You may see lots of different tire sizes available – don’t panic! – unfortunately, bike tires that are only close enough to your tire size probably won’t fit your wheels correctly. This would likely lead to problems like punctures. However, you will have to choose between (i) which brand to buy and (ii) how much ‘tread’ you want i.e. how grippy. With bikes that are just going to be used on the road, I’m usually a fan of smoother tires. They’ll be faster-rolling and normally give less vibration. If conditions are likely to be slippy though it’s best to swap to more knobbly tires for extra grip.
Recently I’ve bought quite a few tires from long-established manufacturer, Continental. I have to say that I’ve been really impressed by the quality of the tires. Fast-rolling and smooth and (so far!) I haven’t had a single puncture. That’s despite putting them through their paces on some tough cycles. If you’re after a recommended tire, then I’d go with Continental Gatorskin tires. Puncture-resistant, lightweight, and fast. A great option. You’ll find them available to buy in a range of widths, so make certain you pick the 700x25mm non-folding ones.
What bike inner tubes should I buy?
Inner tube widths vary depending on how much air you fill them with. As such you’ll find them labeled with the diameter and a width range, e.g. “700×20-25”. For this example, an inner tube with those dimensions could be used for tires of 700×20 up to 700×25.
This tube is a great option from Continental tires. Notice that it has a Presta valve and there are three different widths to choose from – 20-25mm / 25-32mm / 32-42mm.
As we have 25mm tires you have the option of either the 700×20-25 or the 700×25-32. Either will work fine.
The difference is that the 700×20-25 will be lighter (less rubber) but need to be inflated more (so possibly more prone to punctures). Whereas the 700×25-32 will be heavier but more robust. If you have to choose, I would suggest playing safe and going for the 700×25-32.
Be mindful that if your bicycle air pump has a car tire type of valve attachment (known as a Schrader valve) then you’ll also need to get an adaptor like this. This will allow the pump to be used with tubes that have Presta valves like the ones on this. There’s no way to avoid this unfortunately as Presta valves are a different shape and size to the Schrader valves used on car tires. Take a look at the photos on Amazon and you’ll see how easy it is to screw on and use these adaptors.
How do I replace bike tire and inner tube?
If you’ve prepared and got the right gear, then getting a flat tire will be a little annoying but shouldn’t ruin your bicycle ride.
Always ensure that, when you go out for a ride, you take a spare tube (or two), compact repair kit, two tire levers and something to inflate the tube with (either a CO2 tire inflator or hand pump). It can then be an easy half-hour job to get you back on your travels.
There are five steps to fixing a puncture:
- Remove the bike wheel
- Remove the tube
- Find the cause of the flat
- Repair or replace the tube
- Reinstall the bike wheel
For an easy how-to guide, have a quick watch of this video.
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