Cycling

Bicycle Inner Tube Sizes Explained: How to Read 700x28c, 29x2.1 and 26x1.75 (India)

Not sure which inner tube fits your bike? Learn how to read the size on your tyre, match width and valve length, and choose the right tube in India.

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— 3 min read
Ortem butyl inner tube 700 x 25-35c with 60mm Presta valve

Bicycle inner tube sizes explained

If you have ever stood in a shop holding a punctured tube and wondering which replacement to buy, you are not alone. Inner tube sizes look confusing because road, hybrid and mountain bikes use different systems. This guide shows how to read the numbers on your tyre and pick the right tube in India.

Step 1: Read the tyre sidewall

The tyre size is printed on the sidewall. You will usually see one of these patterns:

  • 700x28c: common on road and hybrid bikes. 700 is the approximate wheel diameter in millimetres, and 28 is the tyre width in millimetres.
  • 29x2.1: common on mountain bikes. 29 is the wheel diameter in inches and 2.1 is the tyre width in inches.
  • 26x1.75: older or budget MTBs and city bikes, with 26 inches as the wheel diameter.

Many tyres also show an ETRTO code like 28-622. The second number is the rim diameter in millimetres, and 622 is shared by 700c and 29-inch wheels. That is why one tube diameter can serve both.

Step 2: Match the width range

Tubes are sold with a range, for example 700 x 25~35c or 29 x 1.75~2.35. Your tyre width should fall inside that range. Tubes that are too narrow can overstretch and fail; ones that are too wide can fold and pinch. Examples from our range:

Step 3: Choose valve type and length

Presta valves are slim and common on road and hybrid rims; Schrader valves look like car valves and are common on basic bikes and MTBs. Your rim hole usually decides which fits. Valve length matters too: 48 mm is common for standard rims, while deeper rims need 60 mm or longer so the pump head can grip. For more detail, see our guide to Presta vs Schrader valves.

Step 4: Pick the tube material

Butyl tubes are affordable, hold air well and are the default choice for everyday riders. Lighter alternatives exist, but cost more and are less forgiving of rough roads and pothole-heavy streets, which are a fact of life in many Indian cities.

Quick fitting tips

  1. Check inside the tyre for thorns, glass or a rim tape gap before fitting a new tube.
  2. Add a little air so the tube holds its shape, then tuck it in without twisting.
  3. Use tyre levers, not a screwdriver, to avoid pinching the tube.
  4. Inflate slowly and check that the tyre bead sits evenly all around.

Carry a spare

Keep one spare tube of the right size and valve type in your saddle bag, along with a pump or CO2 inflator. A flat on a hot afternoon is much less painful when you have the right tube in hand.

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Frequently asked questions

Where do I find my bicycle tyre size?

Look at the sidewall of your tyre. You will see something like 700x28c, 29x2.1 or 26x1.75. Some tyres also show an ETRTO number such as 28-622.

Can I use a 700c tube on a 29-inch wheel?

The rim diameter of 700c and 29-inch wheels is the same (622 mm), so tubes for both fit the same wheel diameter. What matters is that the tube's width range covers your tyre width.

Does valve length matter?

Yes. The valve must stick out of the rim enough for your pump head to grip. Deep-section rims need longer valves, such as 60 mm, while standard rims often work with 48 mm.

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