The mountain bike wheel wars are getting even messier this year, with 650B—or 27, or 27.5, depending on whose nomenclature you subscribe to—all the talk at Interbike. Based on an obsolete French standard that splits the difference between 26 and 29, these mid-size wheels deliver the quick, snappy feel of a 26er with the stability and rollover of a 29er, and a dozen manufacturers, including Turner, Ellsworth, Rocky Mountain, Intense, and Litespeed, are rolling out models for 2013. Our favorite so far is the Scott Genius 700, a six-inch, 25.5-pound trail bike built around what Scott is marketing as 27-inch wheels. The top-end Genius 700 SL is a full carbon construction with DT Swiss Nude2 rear shock, Fox 34 Talas Kashima fork, a mixed SRAM XX/XO drivetrain and brakes, and Syncros carbon wheels. We also love Scott’s, ahem ... genius TwinLoc system, which yields three modes of travel from a single bar-mount unit. Happily, the 27 trend won’t be reserved for the top end as Scott is launching the bike in six models—three carbon, two aluminum, and one women’s specific—ranging from $9,000 for the SL all the way down to $3,000.