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I work in the bicycle industry and have never heard nor needed to know the term Flat Folding Width of a tube. Is this even pertinent information to anything other than maybe how many you can jam in your pack? Anyone familiar with or heard this term before? I'm guessing it's the size of a tube when its still folded up with no air, basically right out of the box..

Which seems really pretty pointless to me. It would be on the distribution side of the industry but even to a shop i don't see it having a point as the boxes they come in will be the deciding factor for stocking on a shelf, not the tube inside.

Anyone heard this term or can think of a reason it would be important to anything?

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    Never heard it before - Sounds like packing information. I suppose its also a measure of stretch ratio, if you stick a tube in that is 1" flat folded, and your tyre is 2" it will have a 100% stretch before the carcass of the tyre restrains the tube. Or a 22mm tube in a 25mm tyre will only expand by 15% before being constrained. – Criggie Mar 23 '16 at 1:06
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    Even more odd - google's top result for "flat fold width" is this question. So whoever is using the phrase has possibly invented it. I smell a marketting buzzword. – Criggie Mar 23 '16 at 1:09
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    I think I might have seen the term once, used to describe a tube. It's only relevant to the guy designing the box. Some might argue that it could be used to estimate how much the tube is expected to stretch on inflation or some such, but using flat width for that sort of thing would be exceedingly crude. – Daniel R Hicks Mar 23 '16 at 3:10
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    There is one possible use (outside of the box): You get a bunch of unboxed tubes and are trying to tell them apart. Knowing the width you're looking for will be useful. (But of course a decent tube should have its size marked on the side.) – Daniel R Hicks Mar 23 '16 at 12:51
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I've never heard of that either. Surely useful to a manufacturer of tubes. I could see it being useful in that it might give you a real measurement of how much rubber you are getting. As you may know, bike tires and tubes are measured with nominal numbers that don't actually reflect the real size of the product accurately. So you might be able to tell how wide a tube is without the nominal numbering. Or, if the nominal numbering is accurate.

For example, I've noticed the more recent batches of innertubes we've had at our store are narrower for the same nominal size. This would mean a lighter, thinner inner tube in use (Any size tube will fill the same size space of the tire if possible, less rubber means it has to stretch more to fill the same space). And I've noticed a slightly higher rate of defective tubes. But I haven't actually measured anything, this is just my impression over a period of time. It's hasn't been an important issue.

Inner tubes in bicycles are sized quite approximately and one can usually fit the wrong size tube into a tire to make if work if you have only got that one option. I'm someone who would recommend a thicker tube, as I favour that reliability over the small weight gains. So I would use that information to pick wider, thicker tubes. Others might do the opposite and choose narrow for the weight savings. All of this is assuming consistent quality, which is a big if.

Anyway, I agree with you there is little need for this number to most people. I'm just expanding on the idea to show there could be some use for a very few. Mostly people who overthink trivial matters ;-)

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  • After talking with some more "industry insiders" i think your right. It's one of those numbers that 95% of people won't care about. But essentially what me and some buddies came up with is basically what you said. Say you have 2 tubes, both 26 x 1.50 - 1.95, if one has a smaller ffw then it will be less thick when inflated to the same size essentially. A way to compare Trek apples to Specialized apples. Silly in my opinion though. – Nate W Mar 23 '16 at 14:44

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