Why your GPS is wrong: the Jones Counter is always right

You know how it is: you run a 10 km race, cross the finish line, press your watch... and see 9.8 kilometers.

Or 10.2. Immediately, the reactions follow: "The course was too short!" or "I ran 200 meters too far!" But who actually determines what the correct distance is? And why isn't it your watch?

The answer is surprisingly simple, and a bit old-fashioned: official course measurements are not done with GPS, but with a mechanical device on a bicycle, the Jones Counter.

The real distance starts here

Competitions organized under the banner of the Athletics Union or World Athletics, from local 5-kilometer races to the Olympic marathon, are all measured with a Jones Counter. This device has been the international standard for over forty years.

Here's how it works: a counter is attached to the front wheel of a bicycle that measures how many times the wheel turns. After calibration, the course meter knows exactly how many 'clicks' correspond to one meter. The measurement follows the shortest line across the course. This way, you can be sure that if a course is officially certified, the distance is really exactly 10 kilometers or 42.195 km. No doubt about it.

How an American father and son set the global standard

In the 1960s, Briton John Jewell and American Ted Corbitt began refining the measurement of running courses with a calibrated bicycle. But the big difference was made when Alan Jones, a recreational runner and computer technician from New York, developed a revolution counter and mounted it on his bicycle. When he discovered that a "20 km race" was actually only 11.4 miles long, his quest for precision began.

Together with his nine-year-old son Clain, he assembled dozens of counters, which were eventually used worldwide. The 1976 Olympic marathon in Montreal was measured with it. Since then, almost every major road race on earth has been measured with a Jones Counter. A running effort on wheels.

Why your GPS watch is wrong

GPS watches are fantastic. They give you your pace, heart rate, and splits, but they're just not accurate enough for distance. The deviations are caused by buildings, trees, zigzagging running lines, or the fact that you never run exactly the ideal line.

A GPS can easily deviate by 1 to 2 percent. In a half marathon, that quickly adds up to 200 to 300 meters. So when your watch says, "I ran 200 meters too far," the Jones Counter says, "You probably didn't run the shortest line." Or your watch was just off. It happens.

And what about regional competitions?

It's not just the big city marathons that are officially measured. Many regional races in the Netherlands are also certified. That means: measured with a Jones Counter, approved by the Athletics Union, and valid as long as the course doesn't change, with a maximum validity of five years.

Want to know if your race is official? You can find an overview of certified courses on the Athletics Union website. You can also filter the calendar on Hardlopen.nl for 'certified courses'. Not sure? Ask the organizers. They can usually show you the measurement certificate.

So yes, even your local 10K can be official. And then your time really counts.

When is a course not official?

Some well-known races, however prestigious, are not officially certified. The reason? Too much elevation change or too great a distance between the start and finish.

Think of the Boston Marathon, where you descend considerably. Or the Dam tot Damloop, a point-to-point race with a finish 10 miles beyond the start. The Egmond Half Marathon is also not official, due to the elevation difference and the beach section, which is difficult to measure consistently.

And what does that mean? It means that you cannot set an official personal record in these races. No matter how well you run, it does not count towards your PR list according to the international rules of World Athletics and the Athletics Union.

Conclusion

The next time you think after a race, "Huh, my watch says 10.23 km?", think of Alan and Clain Jones and their simple, reliable bike computer. If the course has been officially measured, then it's accurate. Period.

So don't let a few meters difference drive you crazy. Enjoy your race. Trust the course meters.