Zonhoven is the race of the Kuil, a huge sand pit on the Molenheide terrain in Limburg that the course drops into and climbs back out of three times per lap. The plunge down the sandy walls rewards nerve, and the climbs back out sap the legs every time round. First raced in 1958, it was revived in 2005 after a long gap and joined the World Cup in 2020–21. Mathieu van der Poel holds the record with six wins. In January 2023 he slid on the first descent into the Kuil and, troubled by back pain, could not follow when Wout van Aert rode away to win by 1:23. Three years later, on a course covered in snow and ice, Van der Poel went clear inside five minutes and won alone. It is the hardest sand test of the new year.