Press-fit BB86 frames need a bottom bracket that hits three specs at once: 86.5mm shell width, 41mm inner diameter, and a 24mm bore for the crank spindle. The Shimano Dura-Ace SM-BB92-41B covers all three at a claimed 54 grams, which is 11 grams lighter than the SM-BB9000 unit it replaced in the R9100-series lineup. If your road frame uses the BB86 standard and you're running a Hollowtech II crankset, this is the factory-spec press-fit that Shimano designed to pair with it.

The weight savings come from smaller-diameter steel ball bearings that reduce mass without giving up the load capacity a road bottom bracket needs to handle. Shimano paired the smaller bearings with a reworked seal design that keeps water and grit out of the bearing races, and the sealing package is where the claimed 50 percent reduction in rotational resistance versus the previous generation comes from. That combination is the reason a Dura-Ace-level bottom bracket can weigh this little and still hold up to full-season road use.

Crankset compatibility runs across Shimano's entire 24mm Hollowtech II road lineup — current R9200 Dura-Ace, R8100 Ultegra, and R7100 105 12-speed cranks, along with the previous R9100, R8000, and R7000 11-speed generations. Older 10-speed cranks from the 7900 Dura-Ace and 6700 Ultegra era share the same 24mm spindle diameter and also drop in. Other brands running a 24mm spindle will physically fit, but that combination sits outside Shimano's official support.