At this point in the industry's love affair with plus size tires, we've seen pretty much every possible take on the platform. It's a classic story of Boost meets tire girth, the two retire to a bed of expanded frame clearance, and a squishy little 3in bundle of joy is born. With Pivot's Switchblade Carbon 27. 5 XT Pro 1x Complete Mountain Bike, that classic model of knobby tire romance is pushed in new, lascivious directions. There's a lot going on with this bike, and we'll get to that, but the real naughty element lies in the introduction of what Pivot is calling Super Boost Plus 157, a new rear axle standard that adds an additional 9mm to the rear axle and 12 fecund millimeters to tire clearance. Given the implications of a frame with such titillating clearance, we're a little surprised even disappointed that Pivot didn't call the new standard a sexle. Whatever the case, it essentially combines a DH chainline with a typical 5in bike's Q factor and heel clearance. The introduction of a gravity sized rear axle has serious implications for an aggressive enduro rig, and these implications go well beyond the increased rear wheel stiffness of the more acute spoke angle. The key effect of the sexle err, Super Boost rear hub is that the Switchblade enjoys the clearance to run traditional 29ers or, as is the case here, add an additional element of forgiving, save your ass squish with 27. 5 wheels and tires. Either way, the extra wide spacing allowed Pivot to get freaky with chainstay lengths, chopping them down to 16. 85in by moving the rear wheel up towards the seat tube. That's a dimension that makes standard Boost axles blush, and it pairs with a Phoenix inspired, double wishbone rear triangle to stiffen both the pedaling interface and the linkage design. Increased efficiency and decreased pivot bearing wear what more could you ask for in an off road partner The rest of the geometry is similarly capable. Where the concise back end makes for a sharp knife while ..