FSA sheds weight with their latest KFX mountain bike crank sets by machining, then bonding an interlocking two-piece design that promises a boost in stiffness & strength. But light hollow alloy cranks aren’t all they have in store this year. There’s also an extended AGX gravel bike cockpit line with aero bars & a new dropper, plus more internal cabling options and Super Compact power metering…
FSA KFX light hollow aluminum mountain bike cranks
FSA’s latest top-tier mountain bike cranks are set to leave carbon behind in favor of a new two-piece machined aluminum design. The new KFX alloy cranks take K-Force to a next level, promising a better blend of lightweight and durability vs. carbon. While FSA says they won’t be replacing carbon mountain bike cranks entirely, these do look to be even lighter.
The secret to the KFX’s new XC light, but gravity-ready strength comes down to a multi-stage alloy forging & CNC machining process.
With a modular, spiderless design, each KFX crank arm starts out as two separate forged blanks. Then precision CNC machined into two pieces, the hollowed out halves feature a series of three main ridges & grooves down the outside of each arm that form a tightly interlocking single piece.
FSA then bonds the two halves together with adhesive to create a lightweight, intricately internally machined & hollow crank arm that they say is much stiffer than any of their previous alloy cranks. FSA isn’t the first to bond together MTB cranks, but their internal machining looks impressive.
Another post machining process finalizes the external shape. Then anodizing & other finishing give you the final look, with the construction method revealed by the seam and interlocking teeth visible along the outside of the finished crankarm.
Final details are still outstanding, buy we do know hat the modular direct mount KFX alloy cranks will hit a premium price point as result of the complex machining and many steps in the manufacturing process. Weight is claimed at just 520g for the modular arms & BB spindle, around 15g lighter than FSA’s carbon K-Force cranks.