Am I confused or are they? (Re inner tubes sizes)

[Slowroad]

I'm looking for 32 x 559 / 26” x 1.25 inner tubes for one of my bikes, it seems to be a rather unusual size so I was pleased to find some on a high street car/bike website, but although the pack in the picture has the right sizing, they describe it as 650c. It's quite likely that I'm confused - I often am with wheel sizing! Any advice gratefully received, as ever...
Thanks!

[Jdsk]

You're not alone. The simplest route out of the confusion is to use ISO sizes throughout.

Those tubes fit a range of different sizes of tyre, and give that range as 28/32 - 559/597.

Is 32-559 the size of the tyre for which you need a tube, or does that come from somewhere else?

Thanks

Jonathan

https://sheldonbrown.com/tire-sizing.html
https://en.wikipedia.org/wiki/Bicycle_tire#Sizes

[andrew_s]

650c (597x23c mm ISO) is an old size for a narrow 26" wheel (about 1"), which used to be popular for the front wheel of TT bikes when diiferently sized front and rear wheels were permitted, and hangs on to some extent for racing bikes for juniors and small women, for whom the larger 700c wheel size impacts on a decent frame design.

Tyres used to be sized by outside diameter, so a narrow 26" size needed a larger rim than a wide 26" size, rim size being 26" - (2 x tyre height). There are about 6 surviving 26" sizes, all using incompatible tyres, and all except MTB being sized in fractional inches rather than decimal inches (MTB was originally 26" x 2.0").

Tube sizes always cover a range of tyre sizes, because a tube will mostly just stretch to fit the tyre it's fitted inside.
If the tube is stretched too much, any puncture will be an instantly and completely flat tyre (rather than a slow puncture that gives you time to stop before losing control). It will also puncture more easily, such as due to misplaced rim tape, or something sharp that only sticks far enough through to get halfway through a larger unstretched tube.
If the tube is too large, it will fold back on itself inside the tyre, and in due course it will chafe through at the fold, and you'll get a puncture.

The difference between 597 and 559 is about 2" in wheel diameter, or 6" in circumference.
I'd have thought that would be pushing it for a good fit to both, but that's what it says on the box, which probably means that Continental have sized it to the smaller diameter and are relying on tube stretch for the larger 597 diameter.

I'd therefore be inclined to trust the 559 and 1.3" on the box, and give it a go.

[tim-b]

Hi
There's a better description on this image from the conti website that makes more sense https://www.conti-tyres.co.uk/images/Tu ... 1_1000.png

[Stradageek]

650c (597x23c mm ISO) is an old size for a narrow 26" wheel (about 1"), which used to be popular for the front wheel of TT bikes when diiferently sized front and rear wheels were permitted, and hangs on to some extent for racing bikes for juniors and small women, for whom the larger 700c wheel size impacts on a decent frame design.

Not quite correct; 650C is 571mm, 597mm is the old British 26". I use narrow 559mm (US 26") inner tubes for my 650C (571x23mm) tyres so there is indeed reasonable latitude.

However 650C tyres being so rare I'm considering changing the wheels on my Bacchetta to 26" (559), but first I need some decent long-reach calipers, the current calipers haven't got 6mm of extra reach

[Slowroad]

Thanks all, that is starting to make more sense! At the price it'll be worth me getting a couple of inners, but since posting I've found a few more options too.
To answer Jonathon's question - yes, the tyres are 32-559.

[Jdsk]

Thanks

That's within the manufacturer's range for those tubes.

Jonathan

[mattsccm]

When I had a 650c bike I used to interchange inner tubes at random. In fact the size is close enought that a 26" mtb wheel (559) will often work in the same place.

[NickJP]

At a pinch I've used a tube marked as intended for 559 wheels in 622 wheels when that was all I had available (a friend with deep dish wheels had multiple punctures when we were out on an unsealed road, and the only working spare tube with a long enough stem was one that my wife had on her 26" wheeled bike). I had to stretch the tube to get it inside the tyre, but it worked fine as a tube once installed and inflated.