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The new 26" MTB inner tube is much bigger than my 26" wheel (and old 26" MTB inner tube). I don't understand why. How to shopcorrectly for new tube?

The bike is 1990s Raleigh mountain bike.

Edit: the new tube is very loose both deflated and inflated. The new tube specs are 26 x 1.5 / 1.75 / 2.125 F/V according to the box and tyre

The old tube was 26 x 1.50 / 2.25 according to its box.

enter image description here

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It's not clear -- how much have you inflated the tube? With it uninflated (laying limp) is should fit inside the tire without "bunching up" -- it's normal for it to expand a bit when inflated, and the tire prevents that. (The image above looks close to "normal" for a tube that's been a bit over-inflated.) But as Mike suggests there are (at least) two different standards for so-called 26" tires. –  Daniel R Hicks Jan 7 '13 at 22:30
    
What numbers are on the side of the tire? –  Daniel R Hicks Jan 7 '13 at 22:57
    
(And understand, as Mike says, that 26 x 1.5 is NOT the same as 26 x 1-1/2.) –  Daniel R Hicks Jan 7 '13 at 22:58

1 Answer 1

Check the label on the tube - does it say '26 x 1 3/8' by any chance? If so, this is actually a completely different size than the standard MTB 26". Get a tube that says something like 26x2.1 or 26x1.9 - the point is, the tire width should be expressed as a decimal, not a fraction. See Sheldon Brown's tire size chart.

Yeah, I know, it's stupid - I didn't come up with this system.

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+1 I've been buying tubes for 15 years and I did not know that. –  cmannett85 Jan 8 '13 at 9:18
    
the ISO size of a real MTB tyre is 559mm andthe one in the picture is the old touring size of 26 x 1 1/2 is 584mm (which is making a comeback as a 650b mtb size) –  Callum Wilson Jan 8 '13 at 12:46

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