For 2014 Pivot has redesigned their Mach 6 chassis around the 650B format for better handling and control.
"The Mach 6 features the next generation of long travel dw-link design.
With features like 6.1” (155mm) of travel, a low BB height (13.6”),
longer top tubes, lower stand-over, and a slack head angle (66
degrees), built around an ultra stiff and responsive carbon chassis,
the Mach 6 is a bike designed to push your capabilities and reward
those willing to push the limits. We optimized the design with
internal top tube cable routing, internal dropper post routing, ISCG 05
tabs, and a look that screams of speed. The Mach 6 absolutely rips
for the aggressive trail rider."
The Les is also available as a 27.5 version. And now in more frame sizes!
"Getting your race ready LES under 20lbs will not be an issue. The
biggest news is the small and additional X-small LES frame size that
opens up the opportunity for shorter riders to get on properly fitting
bikes with bigger wheels. Now you can own, ride and race the most
highly optimized hardtail ever created with geometry, stand over
clearance, weight, and ride tuning perfected for the smaller rider. The
LES 27.5 is a truly exciting bike that we are excited to bring to a
whole new legion of Pivot riders."
These 2 frames follow form and function after Pivot's success with their Firebird 27.5 boasting 6.6" of rear wheel travel. See more at the Pivot home page.