On Fri, 23 Feb 2018 03:34:42 +0100, Emanuel Berg
wrote:

So the viscoelastic property is what makes the
tire deform/recover as it rolls
in under/away from the weight of the
bike&rider, and this is hysteresis, and the
result is loss of energy (as heat), and this is
one component of overall loss of energy which
is bunched together as rolling resistance?

No.

The visoelastic means that the material can be both viscous and
elastic at the same time. Apply some force and viscous materials flow
or ooooze. Elastic materials compress under the same force, but
return to their prior state when the force is removed.

Rubber follows a hysteresis curve such as:
https://revisionworld.com/a2-level-level-revision/physics/force-motion/solid-materials/rubber
or:
https://www.google.com/search?q=rubber+hysteresis+loop&tbm=isch
The area inside the loop represent the energy converted to heat by
rolling down the road.

The largest factor in rolling resistance is this energy loss.

There's a section in the Bicycle Science 3rd
edition book covering the details of
measuring rolling resistance

I should get that book...

The first and 3rd editions are quite different. Methinks that 3rd is
the best, but there was quite a bit of interesting stuff deleted from
the first. I have both.
https://www.alibris.com/Bicycling-Science-David-Gordon-Wilson/book/17828968

Maybe disintegrate a tire and put a piece of it
in a stand or a vice? Or/and perhaps fixate the
durometer as well, like a shop drill?

Yuck. You'll find that a bicycle tire under pressure produces a
slightly different hardness measurement than one laid flat on a table.
The thinner the tire, the larger the difference. You want the
hardness under operating conditions, which means inflated and with a
rider on the bicycle. Again, the difference is not huge, but it is
measurable.

BTW how do ISO/ETRTO measure the tire width?
I've heard it is from one bead, over the tread,
to the other bead, this distance divided by
2.5? Do they also disintegrate the tire before
doing this or do they use a string of some kind
to loop around?

I have no idea and am too lazy/busy/burned-out to look it up for you
right now.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558