New Castle Trails’ 2026 Downvalley Dirty Dozen is a reimagining and celebration of trail running, mountain biking, music, and community. The weekend is full of fun including live music from regional bluegrass bands, plus mountain biking and trail running races for all ability levels on the Colorow and Highlands trail networks. Racers can also enter the duathlon option to run and bike!  Cash and gear prizes will be awarded for each race. See the website link for registration, course maps, race results, and race details.

The Dirty Dozen Trail Running Race is a fun and challenging 10K trail running race on the Colorow Trail Network, Sunday 8/2 · 8:00 am start from Alder Park · ~1,100 ft of climbing · $75

If competing in one race just isn’t enough for you, register for both the MTB Race (20-mile course) and the 10K Trail Running Race and you’ll get your own combined category. Awards for Run and Combined categories will be held after races on Sunday.