Circadian Rhythms offers a brief but engaging trad climb tucked into the south-facing walls of Boulder Canyon near Castle Rock. From the moment you step into the chimney just left of Tongo’s angled ramp, the climb invites a hands-on approach that blends chimney technique with face climbing precision. The chimney beckons quietly, its narrow confines pushing you to negotiate tight moves and find the rhythm between squeeze and stretch. Once at its top horn, there’s a natural rest point to sling before committing to the face above. Here, the crack demands careful gear placements, but be ready for some placements that might feel a touch loose or rattle under weight — a classic Boulder Canyon quirk that keeps your gear sense sharp.

Greg Hill’s early ascent shaped the route’s character, patching the crack with RPs to make it a reliable runout that still requires respect. After battling the short, technical chimney, the route shifts smoothly to a thin section leading straight up to a ledge that creates a natural pause in your ascent. From this ramp, a deliberate traverse right links you into the established anchors of Tongo, where you’ll prepare for your rappel back to the ground.

At just 60 feet, Circadian Rhythms packs a compact dose of Boulder Canyon’s character — gritty protection, modest exposure, and the satisfying blend of chimney moves with face climbing. It’s not an all-day project, but a quick test of technique and gear judgment that suits climbers looking for a brief trad pitch with just enough challenge to sharpen skills. Wear sticky shoes and bring a rack heavy on small cams, RPs, and stoppers. The south-facing aspect promises reliable dry conditions most of the year, especially in cooler months when the rock maintains its friction.

The approach is straightforward from the Castle Rock trailhead, dropping into Boulder Canyon with well-trodden paths and a mellow 15-minute walk to the base. Keep an eye out for loose rock on the chimney and stay steady on the traverse section—it’s not long but demands precision, as gear placements here can be tricky. Circadian Rhythms isn’t a flashy line, but it offers an accessible introduction to Boulder’s trad terrain, bridging chimney technique and face climbing on solid natural features with the payoff of great views down the canyon.

Ideal for mid-morning climbs to avoid the afternoon heat, this route fits well into a half-day outing with plenty of other climbs nearby. Whether you’re sharpening crack skills or seeking a brief taste of Boulder Canyon’s character, Circadian Rhythms delivers a compact but rewarding trad experience wrapped in a manageable package. Make sure your rack covers small cams and multiple RPs, and be prepared for a controlled rappel from Tongo anchors. This route’s straightforward access and approachable length make it a practical choice when time is limited, yet the rock still calls.