[whpva] Re: 200m "low/zero" altitude *difference* category
- From: Theo Schmidt <sus2006@xxxxxxxxxx>
- To: whpva@xxxxxxxxxxxxx
- Date: Mon, 06 Feb 2017 18:27:48 +0100
Toni wrote:
...
the altitude of the start of the runup may not be higher than the
altitude of the finish of the runup, i.e start of the timing section.
This is not very useful, because it gives the option to have the start
of the runup at the beginning of a hill, making the second part of the
runup very gravity assist.
To prevent this one could define a maximum slope of say 2/3% ;-)
Yes, it needs a second condition which prevents having the start of the
runup at the beginning of a hill. The easiest and most logical option is
to disrule hills completely (i.e. no part of the runup may be higher
than the finish), but this may be too strict, e.g. requiring the the
finish of the runup (and start of the timing section) to be on the very
highest point of a round course, and also disallow using the banked
curves at all. This is why I suggested a "hill-tolerance" of 1.5m, but
this is rather arbitrary and I have no idea if it is really a good value
to use.
Your idea of adapting the existing 2/3% rule as a maximum slope plus or
minus in direction of travel is a good one but just as arbitrary even if
historical. Maybe relax it a bit to 1%?
...
A dip will also give an advantage, there's a nice youtube video about
that, that I'm to lazy to search for right now. But if it's within
limits I'm willing to accept that.
I'm pretty sure that a dip (any dip) in runup gives no physical
advantage as long as the finish is no lower, but can't prove it. It *is*
clear that a dipped course *is* faster than a straight line from point A
to point B, as initial acceleration is faster, but this is irrelevant
for the runup, whose only purpose is to accumulate speed and hence
momentum and kinetic energy from human power to a maximum at the end of
the runup and over any desired period of time. The additional
acceleration due to gravity in the downwards side of the dip is exactly
compensated by deceleration on the upwards side, that is the net speed
gain due to gravity is zero *provided* the runup and timing sections are
considered *separately*.
There are probably pysiological and technical advantanges, but this is
OK. In any case there are also higher resistances to be overcome do to
the higher average speed. I therefore think that a dip would not be
helpful in the timing section and need not be disruled, but again can't
prove it.
Only measure at three points: start of the runup, finish of the runup =
start of the timing section, and finish of the timing section. Accuracy
This gives no information about the shape of the runup. We need to
have some limits about the "bumpieness" of the road and a procedure
how to measure it.
You're right: we need the three values and at least one or two more
values giving the maximum dip or the maximum hill of the runup and the
timing section. If my thought is correct, we don't need the actual
values of dips, just proof that there is no hill in the runup, or that
it is lower than the tolerance allowed.
We really need to do some simulations in order to get a better idea as
probably nobody here can offer a mathematical proof. However we could be
on the safe side by adapting the 2/3% max slope rule and relaxing this
if proof becomes available.
Best, Theo
Other related posts:
