Karl XII rittet is a mountain-bike race at Nyborg, just outside Halden in southeastern Norway, run over a late-September weekend as part of the NC Terreng Rundbane Norgescup. The program covers cross-country Olympic racing, or XCO, and short-track racing, or XCC. The XCO race carries UCI Cat 1 status, while the XCC race carries UCI Cat 3 status, so the weekend serves both serious ranking-focused riders and younger categories from age six upward.
Halden CK and Idd SK organize the event on purpose-built MTB courses that riders can train on before race weekend. The lap mixes singletrack, technical features, rock gardens, and shorter gravel sections. It may look fairly flat at first glance, but the surface changes often, so riders keep working instead of settling into a steady rhythm. The race also closes the NC Terreng Rundbane season, which gives the Halden weekend extra weight for riders following the national series.