Sunrise to Sunset

Twelve hours. One loop. Infinite laps. Sunrise to Sunset is Castle Rock’s marquee mountain bike endurance race, dropping riders onto Philip S. Miller Park’s 6.5-mile singletrack loop at 7 AM and not calling time until 7 PM. The course runs almost entirely on singletrack — flowing, punchy, and technical enough to stay interesting after hour eight — with short climbs and rewarding descents that reward smooth riding over raw power.

Solo riders go it alone for bragging rights; teams of 2–5 split the suffering in relay format. Categories span ages and genders, including junior, geezer, and coed options, so there’s genuinely something for everyone from the XC racer to the weekend warrior who just wants to ride trails all day in good company. You’ll need a USA Cycling license and an entry fee (solo from $125), but the format means you can set your own pace and goals throughout the day.

Philip S. Miller has solid amenities — parking, restrooms, and the kind of course infrastructure you’d expect from Rattler Racing’s well-run events. Pack for a full day in the sun: sunscreen, multiple water bottles or a hydration pack, and enough food to fuel hours of trail riding. Teams can set up pit zones to cheer each other through the late laps when the legs start to go.