Pivot Mach 5.7 Carbon XX
It doesn't get much faster than this; a SRAM XX equipped carbon Mach 5.7 is the most deserving of the "Mach" series name out of all the Pivot Bikes. With XC-like weight in a laterally stiff platform that Pivot is renowned for, the Carbon mach 5.7 is a dangerous weapon for reaching top speed on technical and choppy singletrack. Sure there are some lightweight carbon 6" bikes on the market, but none of them have the same low-slung geometry, pedalling efficiency, frame stiffness or high speed stability that the Mach 5.7 seems to effortlessly exude. 
If there is one thing in particular that Pivot Cycles is renowned the world over for, it would be for its innovation in frame & suspension technology, and the introduction of the Carbon Mach 5.7 is a glowing example of this quest for continual improvement. The alloy Mach 5.7 had already received rave reviews and a consensus amongst MTB journalists that it was the stiffest bike in its class, though not being one to sit on their laurels, Pivot have taken the industry by storm and brought forth a lighter and actually stiffer again, carbon model. Based around the same 145mm travel dw-link suspension design as the alloy model, the Carbon 5.7 uses the same low & slack geometry that gives you that invincible feeling when pointing it downhill. Because of the anti-squat characteristic of the dw-link design, Pivot are able to get away with a lower than standard bottom bracket height without fear of clipping pedals on rocks due to soggy rear suspension. The lower BB gives a lower centre of gravity and allows the rider to absolutely rail corners with traction and control that is akin to a 4X bike. Of course the Carbon model gets all the gizmos and gadgets like all the latest Pivot dual suspension bikes, such as the 142x12 thru-axle, Tapered headtube, PressFit XTR BB and one-piece carbon rocker, as well as some new features like the integrated rubber frame protection and cable routing guides for a dropper post.

For those who believe carbon belongs on road bikes and XC race hardtails, the question still remains; why make a 145mm trail bike out of carbon fiber? The carbon fiber construction used on the Mach 5.7 Carbon houses a number of clever features that Pivot have used to maximise the advantages of using the black magic material, such as the internal molding technology that shapes the carbon on both the inside and outside of the tubing. This allows for a very consistent finish to the frame that reduces unnecessary material (weight) and decreases stress risers (strength). All of the molds are unique to Pivot Cycles and show designer Chris Cocalis' sheer determination in providing genuine innovation to further the performance of their bikes, rather than simply sifting through a catalogue and picking out a tacky carbon frame to put their sticker onto. With the goal of improving ride quality and lateral stiffness as their number one priority, the fact that the 5.7 Carbon is lighter than its metal sibling is simply a bonus. That may shock a few leg-shavers out there, but the reality is that Pivot make great-riding mountain bikes first and foremost with performance and durability like no other.