"Rob Morley" wrote in message
news:20181020233448.60296533@Mars...
On Thu, 18 Oct 2018 12:43:41 +0100
"Jim GM4DHJ ..." wrote:

yip 28 inch


English "28 inch" or German "28 inch"? There's half an inch difference
in the diameter of those.

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
millimetres.