For a square circuit of 500 meters length, a 5 km race will take 10 laps. The skater will make forty 90 degree turns. If he skates on the centerline of a 10 m wide road, he will be 4.7 m farther out that he would be if he was skating 30 cm from the curb.
Forty 90 degree turns is ten complete circles. Each circle taken 5 m out rather than 30 cm out will be 29.5 m longer than the 30 cm path. Over ten circuits this adds up to 295 meters.
If the 500 m course is measured on the centerline, a skater using the shortest route (30 cm from curb) will travel 295 meters less than 5 km when skating 10 laps.
Other configurations will lead to other differences.
Where can one access in-line skating measurement rules? I was not aware they had any.
In-line skating races seem to be increasingly piggybacked on top of regular footraces. The people who measure the courses can have more work to do if the definitions of the proper measure lines for running and in-line courses are not the same. First, measure the course using the SPR. Next, do it all over again using the middle-of-the-road.
It would be perplexing to both the runners and skaters in a 10 km race if there were two different start lines and a common finish for the same supposed 10 km race.
If the in-line skating event is a stand-alone event, there will be no problem. If it’s combined with a running event, somebody’s got some thinking to do.