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.
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.
You can essentially inflate the tube out as much as you want until it pops. If you over inflate it before mounting it, it wont fit. Try using less air. Generally, also, tubes are marked for a certain size of tires, so try to match that too (if the tube is too big of a size, you may have it fold over itself, while if its too small the tube may be effectively a bit thinner than you like, but there is some tolerance in this - one or two sizes either way from the tire probably won't make a difference provided you're using the right diameter and both the tire and tube are sold as fractions or decimals).
You might be better of if you compare ERTO-measures for your tires.
A 26 × 1 1/2 (= 26x1.5) is a 40 - 584 in ERTO, which is 40mm wide and 584mm in diameter. A 26 x 1,75 is ERTO 47 - 559 which is wider an has a smaller diameter.
Modern tubes tend to cover a wider range of tire sizes. Not everyone appreciates this. If the tube fits without folds it will do the job.
