Registration is now open for the Horner Cycling Foundation’s Thrilla Cyclocross Series. There are no entry fees, as it is a donation-based event series.

The series runs on four Thursdays (Sept. 12 through Oct. 3) at the Athletic Club of Bend. Registration is available at obra.org.

Cyclocross is the sport of racing bicycles over rough terrain that usually requires carrying the bicycle over obstacles. Cyclocross bikes are not required but encouraged.

The course is a lap around the Athletic Club of Bend, clockwise. Each lap is close to two miles. Racers complete as many laps as they can in 30 or 45 minutes, depending on their race category.

The course is mostly singletrack and loose dirt with two barriers and a sand pit.

Participants are encouraged to donate to assist with covering the cost of the event, in lieu of race entry fees. OBRA memberships are required and are available online and at the races.

Day-of registration begins at 3:30 p.m. Thursdays at the Athletic Club of Bend under the OBRA tent. Racing starts at 4:20 p.m.

For more information, visit hornercyclingfoundation.org.

— Bulletin staff report