Big BM stands out as the singular crack route gracing the rugged Onyx Summit Crag, situated along the Highway 38 Crags in California’s San Bernardino Mountains. This climbing line invites adventurers into a left-facing corner system, carved between the main pillar and the adjacent right face. While it may initially appear modest from below, the climb unpacks into a gratifying sequence of moves that challenge both technique and composure. The corner itself offers jams and laybacks with reliable rock quality, rewarding steady pacing and focus. About halfway up, a comfortable ledge provides a natural rest spot before the route transitions to short face moves past a single bolt. These final moves test balance and edging skills as you approach the bolted anchor system marking the top.

At roughly 50 feet, the climb is compact but demands precise footwork and confidence with hands and fingers locking into cracks up to two inches wide. Protection is straightforward, with placements for gear up to two inches complementing the one bolt that cushions the upper face section. The area is surrounded by pine and scrub, lending a quiet backdrop where the occasional breeze carries the scent of resin and fresh earth. The San Bernardino Mountains offer a rugged setting, with panoramic views of distant ridgelines that lightly scratch the horizon, reminding climbers of their place amidst vast, unyielding wildlands.

Approaching Big BM is accessible yet requires attention: the trailhead lies just off Highway 38, where a short approach trail gains 10-15 minutes of steady terrain, crossing forested patches with loose rock underfoot. Timing your climb in the cooler morning or late afternoon hours can enhance comfort, as the wall faces east and catches direct sun during midday. With a solid 5.9 rating, Big BM sits at the threshold between comfortable and challenging for many trad climbers, offering enough push to sharpen skills without overwhelming those newer to crack climbing. This makes it an excellent introduction to traditional crack systems in Southern California.

For climbers preparing to send, emphasizing proper footwear with sticky rubber will aid in smearing on the face section, while finger strength and jam technique will smooth the corner work. Carrying a full set of cams up to 2 inches ensures safe and confident gear placements, and double-checking your anchor rigging at the top is crucial for a secure rappel descent. The region’s variable weather means checking forecasts is wise; summer afternoons can grow hot and dry, while winter mornings may surprise with chill.

Big BM embodies the balance between an accessible challenge and a rewarding technical climb, perfectly suited for those looking to extend their trad repertoire without venturing into ultra-remote terrain. It invites a measured engagement with the rock, where every jam and face move feels earned, and the final relief at the anchor is both a goal reached and a moment to absorb the quiet grandeur surrounding you.