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A technical question of odometer calibration preferences. Feedback sought…

As I continue my roadbook rally journey as an event organiser, I continue to compare what I'm doing to what other event organisers do - adopting established practices when it seems sensible and innovating when I can't see the sense in doing "it" the way others do "it" in different circumstances eg cars on tarmac roads.

One of the "customs and practices" appears to be including a odometer calibration section at the start of each route. I'm not sure about the value of this and wish to canvass opinions.

Firstly, odometer calibration. You do this, right?

The gps odometer in Rally Roadbook Reader can be toggled between mph and kph and has a calibration offset of +/- upto 10%. Your bike odo will always read wrong, up to a maximum of +10% plus 10kph... About as useful as a chocolate teapot if you are doing a TSD rally.

The calibration page in Roadbook Reader looks like this:

To calibrate the app odometer you need a distance of road of known length, zero the odo, ride the road and see how the numbers in the app compare to the known road distance. Alter the %offset and try again, zeroing-in on the error (if you can forgive the pun....).

I have done this on my Rally Roadbook Reader, setting a 5km road distance in Gaia and riding the route again and again to zero the app odo.

The (pc) computer system to write the roadbooks is Rally Navigator. Rally Navigator uses Google Earth images as the basis for its mapping system with roads from another mapping system overlayed. The Google Earth positioning of roads does not always closely correspond to the road information and so it is sometimes a bit hit/miss to know exactly where to put the route marks...

So, it appears the more accurate/precise mapping system is Gaia - every time I have used it to record my progress on a ride, the route track is always very close indeed to the road position shown on the Gaia map.

Of course you are just as capable of marking out a Gaia road route of known distance as I am, and you can conveniently do it close to your home...

So, if you can calibrate your odometer of choice over a course of a known distance in exactly the same way as I would set a "calibration" course, what extra does my provision of an "odometer calibration course" bring? I can't see any benefit at all. It may be that other event organisers use different mapping systems that event participants can't replicate for ahead-of-time calibration, but given we all have access to and use the same systems.....?

Knowing all this, is there any point in me providing an odometer calibration course on the event? Opinions sought...


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