What Size Inner Tube Do I Need For 700x25c Tyres? (Answer & Recommendation)

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Ben Jones



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Working out what inner tube you need for your bike can be a tricky business, can’t it?

It should be so simple, ideally with a one-tube-fits-all-bikes type available at your local bike shop.

But, unfortunately, that’s not the case. Whilst Henry Ford would be pleased that they’re only available in black, he would be less than pleased about the multitude of different sizes that they come in. Not exactly the Ford Model T way of doing things.

Half the battle with bike tubes is working out what size tyres you’ve got and here you have a major advantage – you know that you have 700x25c bike tyres.

So, I’ve got two things for you today (and a bonus):

  • A simple answer for what inner tube you need
  • My recommendation for the best tube for your bike tyres
  • BONUS – a quick refresher in how to change a tube (if you’re feeling a little rusty!)

700x25c inner tubes

Continental Race 700 x 20-25c Road Bike Inner Tubes

This is a great set of inner tubes from Continental.

First up, they’re the perfect size for your bike tyres. They’re 700 x 20-25c, which means they’ll fit bike tyres from supermodel-skinny 700x20c to your slim ‘n’ athletic 700x25c.

Next up, they come as a multipack of 3 tubes. Why is this useful? Well, much like waiting an hour for a cab, and then three turn up at once, I generally find that punctures come in groups. If one tube blows then there’s a decent chance that the second (being a similar age) is about to go the same way.

I also like to take a couple of tubes out with me when I go for a bike ride. Changing a blown tube is simple enough (I’ve got a refresher guide on this below) but, when you’re all fingers-and-thumbs like yours truly, tearing a new tube as you’re trying to fit it isn’t out of the question. So it’s good to have a spare spare, if you know what I mean.

The tubes are manufactured by well-respected tire company, Continental. Who have been in business for over 140 years! So they know a thing or two about tyres and tubes. I’ve used Continental tubes and tyres on various bikes for many years – not 140, in case you were wondering – and have always been really pleased with the quality and durability.

If your pump has a Schrader valve (the type that works with car tires) then you’ll need to invest in a Presta adapter. These are cheap to purchase and mean that you can use either a Presta or Schrader valve pump to inflate these tubes.

The adaptors are great. Easy to fit onto your valve where you can either leave them, or tuck them into a saddlebag. They mean that you can then use a Schrader pump with any Presta valve.

READ THIS NEXT How to Choose the Correct Types of Tyres for Your Bike

700x25c vs 700x25mm – What do the numbers mean?

Just in case it ever comes up in a pub quiz, let’s take a look at what the numbers mean.

‘700’ is the nominal diameter of your tyre in millimetres.

‘x’ is multiplied by.

‘25’ is the nominal width of your tyre, again in millimetres.

‘c’ is where it gets a little weird…

The ‘c’ harks back to the old French system of dividing up bike tyres according to their width. ‘a’ tyres were the narrowest, up to ‘d’ tyres which were the widest. Even though the system has been superseded by metric, imperial, and ISO/ETRTO measurements it is still, oddly, included on tyres. From the perspective of choosing inner tubes you can ignore it. A tube that says it is for ‘700x25c’ will be the same as one that says ‘700×25’.

READ THIS NEXT The 2 main types of bike tire valves and how they work

How to change an inner tube on a road bike

There are a number of steps to replacing a tube:

  1. Remove the Bike Wheel by releasing the brakes and undoing the bolt or quick-release to loosen the axle
  2. Remove the existing tyre using a set of tyre levers
  3. Remove the inner tube – deflate it first if needed
  4. Check for the cause of a flat tire – such as broken glass or a nail, so you can remove that and it won’t happen again
  5. Repair or replace your tube
  6. Put the repaired tube (or a new tube) back on the wheel
  7. Fit the tyre
  8. Fully inflate the inner tube and check the pressure
  9. Re-fit the wheel on the bike and reconnect brakes
  10. Check smooth operation of bike, including brakes

For a simple video on replacing a bike tube, take a look at this YouTube: