Riders replacing a worn Octalink bottom bracket on a 68 mm English-thread frame, with a crankset that calls for a 113 mm axle.
The BB-ES300 is Shimano's Octalink bottom bracket for Alivio-level mountain and trekking cranksets. It is one sealed cartridge unit with a hollow steel spindle, a resin left-hand adapter and a steel, phosphate-coated right-hand shell.
This is the 68 mm English-thread (BSA) version with a 113 mm axle. The axle length sets your chain line, so match it to your crankset as well as your shell: Shimano's chart, for example, pairs the Alivio FC-M4000 with a 118 mm axle, so check what your crank needs before choosing 113 mm.
Hollow Octalink spindle
The 8-splined Octalink interface adds strength and rigidity to the whole assembly, says Shimano.
Sealed cartridge unit
Bearings and spindle sit in one sealed unit that fits and swaps as a single part.
Chain stabilizer
Shimano lists a chain stabilizer for good chain line control.
68 mm English thread
BC1.37 x 24 threading for 68 mm shells, with a 113 mm axle.
Fit
Build and install
Great for
Maybe not for
Confirm the shell width (68 mm) and English thread, then match the axle length to your crankset. This one is 68 mm with a 113 mm axle. Shimano also makes the BB-ES300 for 73 mm and 70 mm shells and in 118, 121 and 126 mm axles, and those are separate parts, including a 73 mm shell version with the same 113 mm axle.
Shell width and axle length are separate numbers
The shell width has to match your frame, and the axle length has to match your crankset and chain line. Shimano's chart pairs the Alivio FC-M4000 with a 118 mm axle and the FC-T4010 with 126 mm, so check your crank before settling on 113 mm. Shimano's manual also says to grease the body, fit the body first and then the cup, tighten to 50 to 70 N·m, and not to grease a plastic cup. The left-hand adapter on this one is resin.
