Round 5 of the Colorado Off-Road Championship Series (CORCS), presented with Slavens Racing, takes over Thunder Valley MX on August 1 and 2, with a Pro/AA purse of $500 plus 100 percent of entry fees paid back to 30 percent of the field. Saturday runs the minis and more: sign-up at 7 AM, riders meeting at 9, then six races from Mini 4/Super Mini through Mini 1, plus Women Beginner, Quad Mini, and a 3 PM Vintage race. Sunday is the big-bike day: sign-up from 5:30 AM, C-class practice at 7, then waves through the morning (C250/Youth, C Open/C Vet/Sportsman, 60+/Women/Electric/Vintage/40+ 150, C Senior 40+ through SUP 65+), A/B practice at 1 with the A/B race at 1:30, and quads closing the day at 3:30. Pre-entry saves money: Saturday $35 ($45 race day), Sunday A/B/C $60 ($70 race day), Sunday Pro $70 ($75). Gate is $15, $10 for 12 and under, Saturday spectators FREE, and camping opens Friday. CORCS is AMA sanctioned: current AMA membership and the 2026 annual waiver are required before check-in. The course mixes vet-type MX with off-road terrain.