Shimano 105 FC-R7100 Crankset - 170mm 12-Speed 52/36t 110 Asymmetric BCD Hollowtech II Spindle Interface BLKShimano 105 FC R7100 Crankset 170mm 12 Speed 52 36t 110 Asymmetric BCD Hollowtech II Spindle Interface Black. The Shimano 105 FC R7100 12 speed crankset offers an optimized balance between lightweight and efficiency without sacrificing stiffness. The crank is formed with hollow aluminum technology and finished with a durable gloss black anodized. The resin ribs on the back of the chainrings are Shimano 105s unique structural design that achieves both