The most incredible aspect of the recent King of the Motos motorcycle race is not that only six of 21 riders managed to complete the grueling 65-mile course.

It’s that six riders did complete a three-hour marathon that entailed navigating across sand-filled washes and ominous-looking boulder fields that for most of the field were impassable.

Some riders implied that the first-ever event, staged in the desert near Barstow, Calif., might have been the most extreme off-road motorcycle race ever (see video below).

It featured invited riders known for their expertise on harsh terrain. But down they went, one by one, either from exhaustion or mechanical breakdowns (riders could not receive pit-crew support).

Dirt Rider magazine editor Jimmy Lewis, who co-directed a competition patterned after a similar race for four-wheel-drive vehicles, described King of the Motos as “a motorcycle survival race.”

Most of the damage was inflicted on a 10-mile stretch of fraught with boulders. Trial-riding skills were required to make it over some of the larger obstacles, and crashes were frequent and, in some cases, painful.

The course contained few markings, so riders relied on GPS units to maintain a proper line. And when the dust settled in this bone-rattling struggle of attrition, British endurance specialist Graham Jarvis was the winner, with a time of 2:57:19.

The Husaberg rider’s prize was $10,000 in the winner-take-all event, but five others deserve mention merely for finishing: Kyle Redman (second place), Destry Abbott, Mike Slawson, Cody Webb and Jimmy Jarett.

Presumably, their kidneys are thankful that this competition will not be held again for another 12 months.