It looks like the days of chainring standards for high end cranks may be numbered. Following in the footsteps of Shimano, FSA’s new K-force Light BB386 crankset sheds the traditional design in favor of an asymmetric design, only FSA’s still has 5 arms. Hidden behind the crank arm is the 5th bolt, part of a system that was strategically placed in the locations where the pedaling stresses are concentrated. The hollow carbon arms feature a UD finish and hidden bolts and spindle for an improved look and aerodynamics.
Shift past the break for more.
FSA calls the new bolt spacing ABS – or Asymmetric Bolt Spacing which is still apparently built around a 110 BCD, though the spacing won’t line up with a standard 110 ring. Since a rider’s power output is not consistent around the circle, the arms were placed where the points of stress are highest allowing for a super light design that is still stiff. We have already reached out for an answer on this – but if it is based on a 110 BCD then the crank may be able to run both standard and compact rings on the same arm like Shimano’s 9000 crankset. Also, the fact that the crank is only available in 386 is mitigated by the fact that FSA includes bottom brackets that will adapt just about any frame to use the 386 EVO spindle, even threaded. Update: standard and compact rings will be based around 110 BCD so the crank can run 46/36T, 50/34T, 52/36T, and 53/39T chainring combinations. This is a welcomed trend as riders can change to a compact or even cross gearing without having to buy a new crank if need be. Also, FSA’s new ABS chainrings have new optimized teeth and shift ramps for improved shifting.
The K-Force Light weighs a claimed 584g with a BB386 spindle and will include 7075 aluminum chainrings with alloy T-30 Torx chainring bolts and will be compatible with Shimano 11 speed chains. Arms will be offered in 170, 172.5 and 175mm lengths and in red or black graphics. For more on the crankset check out FSA’s video, which we didn’t embed here due to the auto-play.