NON-FLAT CALIBRATION COURSES
A question arose when a certificate for a calibration course with a drop of 15 m/km was received. Should such a cal course be certified or used?
The ideal calibration course is straight, flat, at least 300 m in length, and close to the course to be measured. In many cases this ideal is hard to achieve. There’s no wiggle room on the length nor on straightness, but how much elevation change is OK? This is not rigidly specified in our procedures. Should it be?
In the group validation measurement of the 1996 Olympic marathon course, the 480 m calibration course had a drop of 4.2 m/km, and had a hill in the middle which was 9 m higher than the low end of the course.
In the group validation of the 2003 Olympic Trials marathon in Birmingham, Alabama, the pre-measurement 300 meter calibration course had a large rise (or drop) of 39 m/km. The postcal was flat.
The above courses were chosen for their proximity to the start of the measurement. It would have been time-consuming and difficult to locate an ideal precal course that did not require mass transport of the bicycles.
In spite of the hills, calibration rides did not show much difference. In Birmingham the typical ride took about 3300 counts. Uphill counts were generally less than downhill, but not in all cases. Moreover, the difference between uphill and downhill was generally on the order of 2 to 4 counts.
My feeling on this is that this is not a problem requiring a solution. Could be that any cure would be worse than the disease.
As long as the cal course is ridden in alternating directions, the errors should cancel out. Perfectly? No. Good enough? I think so.
Also, any windy day will produce count differences depending on whether the measurer is riding upwind wind or downwind.
Commentary?
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