OCT stands for Open Core Technology, with Truvativ joining the very exclusive hollow-forging club. They’ve gone with a straightforward shape in 7050 aluminium that’s impressively low proﬁle, both near your ankles and at the pedals.
The narrow setup means your feet are a good half-inch closer together than on most other mountain bike cranks. It’s not a massive difference but it’s signiﬁcant.
The aluminium chainrings are a versatile 24/36T combination. It’s worth noting that Truvativ’s GXP bottom bracket has deeper cups than the otherwise similar SRAM and Shimano units.
While some BBs are interchangeable between brands, this one isn’t. The axle runs directly on the inner race of the bearing, so you’ll need to keep an eye open. A seized bearing could damage the axle.