FSA

SL-K Light ABS EVO386 Crankset

FSA's upper-end cranks have long featured on custom and boutique builds for a reason, regardless if the rest of the drivetrain was engineered in Italy, Japan, or Illinois. Their desirability stems from the brand's willingness to eschew general industry standards in favor of what works, and the FSA SL-K Light 386EVO Crankset is a strong case in point. It's got stiff carbon crank arms, a reinforced four-arm spider, and can be adapted to virtually any 30mm bottom bracket shell and any size chainrings—a heady features list that means the SL-K Light 386EVO is capable of being all things to everyone.

Compared to its immediate predecessor, the latest SL-K Light Crankset's biggest obvious change is the loss of a crank arm. This brings it in line with what we're seeing from Japan and Italy, but with one key alteration. Where the other brands have reduced their bolt counts to just four, FSA's Asymmetric Bolt Spacing (ABS) features five bolts to attach its chainrings. It uses a 90-degree relationship for the four first bolts but adds the fifth bolt under the crank arm, reinforcing the crank arm-to-chainring interface at the most important point in order create a stiffer, more efficient crankset.

Other than that admittedly big difference, the crankset returns largely unchanged for the new model year. It still features the same uni-directional hollow carbon fiber construction, which produces a figure-eight cross section that runs a bracing structure down the middle of each crank arm in order to further stiffen them. The crank arm attaches to FSA's proprietary BB386EVO bottom bracket system, which features an elongated version of the 30mm spindles used in all PF30 and BB30 bottom bracket designs.

By simply extending the spindle, FSA's 386EVO standard gives frame manufacturers the freedom to flex their tube shape muscles in order to reinforce the bottom bracket junction. Given that stiffness is critical down there, you can bet your ass that countless manufacturers have taken FSA up on this offer. BB386EVO maintains a standard Q-factor while literally expanding bottom bracket shell possibilities, and FSA manufacturers a range of adapters to suit cranks built to the standard for virtually any bottom bracket shell that accommodates 30mm crank spindles. That means that, even if your frameset isn't built to BB386EVO specs, the crankset can still adapt to it.

Since the bottom bracket extends further, the crank arms don't have to bend as much to provide ankle clearance on the frame. That means less material, so it saves grams, and higher torsional stiffness because the crank arm itself is straighter. You know how bowed seat stays provide compliance to absorb road impact? The same is true of bowed crank arms, but the extra compliance works against you by flexing, which hampers efficient power transfer.

The crankset's adaptability extends to its bolt circle diameter. FSA's ABS bolt layout uses a single bolt at each contact point to secure both chainrings and features the same bolt circle diameter for standard, semi-compact, and compact rings. You can swap ABS rings out as necessary depending on what your day of riding has in store. Doing an omnium with a hillclimb and a TT? Go compact in the morning and throw the big rings on in the afternoon. We should caution you that the system is locally universal, which means that the SL-K ABS crankset can swap between different SL-K ABS ring sizes, but it isn't compatible with K-Force or Gossamer Pro ABS crank arms or rings.