Ultra • Backyard • Netherlands

Tikkende Klok Challenge

Tikkende Klok Challenge 2026

6 Sept 2026·Zandvoort·One Hour One Lap (1 lap per uur, max. 10 laps), Last Runner Standing (2 laps per uur, max. 20 laps)

The Tikkende Klok Challenge is run on Circuit Zandvoort, where a single lap measures exactly 4,259 metres. Ten laps therefore make a marathon. The format follows the principle of a backyard ultra: every hour the starting gun sounds again. There are two options. In One Hour One Lap you cover one lap per hour, running or walking, and decide for yourself how long to keep going. In Last Runner Standing it is two laps per hour, with everyone starting at nine o'clock and anyone outside the hour dropping out. The event lasts a maximum of ten hours, which adds up to two marathons. It is a fundraiser for research into the hereditary heart muscle disease PLN.