The PressFit Bottom Bracket cups for Shimano 24mm Hollowtech cranksets have been upgraded with the new XT M8000 11 speed groupset. Bearing size has changed, The new bearings are smaller and reduce rolling resistance for increased efficiency without sacrificing durability. The unit itself is lighter, and a little more streamlined. In addition to the new bearings of the MT800, the bearing seals were also upgraded to better protect from water and mud.The resin body is stiff, while preventing frame damage, and still utilizes the familiar sleeve that protects the inner bearing seals from dirt and moisture that infiltrates the seat tube. Always use the proper bearing press tools for installation, so as not to damage the bearings or frameset. Expect the seals to feel a bit stiff at first, but after a short break-in period, the resistance reduces drastically.

Shimano's PressFit Bottom Bracket was designed for 41mm inner diameter shells, with widths of 89.2 or 92mm. Bottom brackets have been kept affordable, and with proper installation and use, the units have proven quite durable. Remember that on Hollowtech cranksets the crank fixing bolt (star-shaped plastic or alloy bolt that threads into the non-drive side of the crank spindle), is just a bearing pre-load device. This very low-torque bolt takes up slack and pre-loads the bearings. It is not a tightening or retention device. The leading cause of bearing failure in Shimano's bottom bracket system is over-tightening of this adjustment bolt.