It may have been on that bike are you sure was it on the same (sized)
wheel ? Given its possible to fit different size wheels on the same
frame by way of replacements, etc.
Non folding bike tyres have a continuous wire mouded into the bead
which snaps over the rim. While its conceivable that the joint in
this wire may have failed that wouldn't explain why the rubber has
stretched as well
So does Germany actually use "28" in the specification of its wheel
diameter? It must be one of the few measurements in the imperial system that
has survived Europe's use of the SI metric system. Are there any other cases
where items are sold in imperial units (as opposed to being an integer
number of inches which is translated into metric *)? If there is 1/2 inch
difference in diameter of English and German 28" wheels, which one is the
true diameter that you would measure? Is one the external diameter of the
rim and the other the diameter of the tyre bead which is slightly smaller
and has to be levered over the rin?
Incidentally, has anyone actually had to use tyre levers for fitting a
bicycle tyre? I always find that I just tuck the bead in at one side, then
ease it in by moving my thumbs towards the opposite side and then pull it
away from the rim at the very opposite until it pops into place; and vice
versa for removing. You'd think that a lever would be needed at least to
make the bead pop out from the rim when removing, but I've never found one
necessary. Am I unusual?
(*) For example I doubt whether 5 1/4 and 3 1/2 inch floppy and hard disks
are/were advertised that way in Germany, France etc - they'd be specified in
You'll still see their traditional "28 x 1-5/8 x 1-3/8" marked on the
side of many tyres.
Some Germans still use Fuß, Zoll and Pfund as we use foot, inch and
The ISO/ETRTO measurement is the actual millimetre diameter of the
bead/seat, which is the same for the tyre and the rim, although there
are variations in manufacturing tolerances which lead to some tyre/rim
combinations being looser or tighter than normal. The traditional tyre
sizes are based on effective diameter: a fat tyre on a smaller rim has
the same diameter as a skinny tyre on a larger rim, hence you get two
English 26 inch tyre sizes, one with a width of 1-1/4 inch and the
other of 1-3/8, with a corresponding 1/4 inch difference in rim size
which seems pretty reasonable. But there is some strangeness - English
28 inch (28 x 1-1/2 as fitted to vintage "police bikes") is 635mm, a bit
bigger than English 27 inch at 630mm but the German "28 inch" (commonly
called 700C) is 622mm, actually smaller than 27 inch.
Wider tyres on wider rims tend to be easy to fit and remove without
levers, although some cheap tyres can have very thick inflexible beads
that make it harder to get them into the well of the rim, in order to
get that bit of slack to pop the last bit over the edge. Conversely some
wide but very light and flexible tyres (e.g. racing mountain bikes
tyres with Kevlar beads) can be fiddly to fit because they're so floppy
they won't stay on until they're held in shape by the partially
inflated inner tube. Narrower tyre/rim combinations are more likely to
be too tight to fit without levers; I have such a combination on one
of my bikes, and the usual method of strapping the bead into the well
of the rim just doesn't work. That one needs the application of my
workshop-quality steel levers, and it's still not easy. You have to be
very careful not to pinch the inner tube when you're using levers, but
it shouldn't normally be necessary when fitting a tyre - when removing
a tyre it may be quicker and easier to user levers, and if you're going
to bin the tube you don't care about pinching it anyway.
Well I never knew that. I always thought that units such as foot, inch and
pound were peculiar (*very* peculiar!!!) to Britain and countries such as
US, Canada and Australia that had British ex pats. I hadn't realised that
non English-speaking countries had at one time used imperial units.
In Germany, a pound is a half-kilo, 500g , with the definition dating to 1858.
Inch as in "Zoll" is used in plumbing: 1/2" pipe, 3/4" elbow, gasket for a 2"
union. Also in the vernacular, as a "Zollstock", meaning "any yardstick" even if
it's two meters, folding, and not a yard.
"Fuss" (foot) I have never heard used...
Hmm, either the bead wire has broken (on both sides) or you have simply
mis-remembered which bike or wheel the tyre came off. My money is on the
I’ve kept many old bike tyres for years and in my experience, the bead
*never* changes in size. Have you had new wheels put on at any time in the
past? What size did the ruined tyre claim to be in the sidewall? What was
the figure printed on the sidewall of the “stretched” tyre?
That’s nearer 26” than 28”. As I said, it’s most unlikely that the tyre
changed size. Extraordinary claims need extraordinary proof. Post links to
photos of what is *actually* printed on the sidewalks of your ruined and
“stretched” tyre please. Tyres just Do Not Stretch in storage.
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