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BB86 vs BB92: the same standard, two widths
BB86 and BB92 confuse people because they sound like two standards, but they are one 41 mm pressfit design in two shell widths, road and mountain, both built around a 24 mm crank spindle.
One bore, two widths
Both BB86 and BB92 use a 41 mm smooth shell bore into which bearing cups press. The bearings are sized for a 24 mm Shimano Hollowtech II style spindle, or a 24/22 mm SRAM GXP spindle with the correct cups. The names come straight from the shell width: BB86 is 86.5 mm wide for road frames, and BB92 is 91.5 mm wide for mountain frames.
Because the bore and bearing are identical, the cranks that fit are the same family. The wider BB92 shell simply spaces the bearings further apart for a mountain frame's wider rear end and tyre clearance.
What fits a 41 mm pressfit shell
A 24 mm spindle crank, such as Shimano Hollowtech II, is the native fit using a 24 mm pressfit bottom bracket. A SRAM GXP crank fits with a GXP-specific pressfit unit that steps the non-drive bearing to 22 mm. A 30 mm spindle crank does not natively fit a 41 mm shell, because the bore is too small for a 30 mm bearing, so it needs a reducer bottom bracket that runs the 30 mm spindle on smaller bearings inside the 41 mm bore.
This is the usual trap: people try to fit a 30 mm crank to a BB86 or BB92 frame and find they need a specific reducer, not a standard pressfit cup.
Creak and service
Pressfit cups in a 41 mm shell can creak if the shell faces are not clean and parallel or if the cups are pressed dry. A thread-together bottom bracket, where two cups screw to each other through the shell, is the common upgrade that cures most BB86 and BB92 creak by removing the reliance on the press fit alone.
Always press cups with the correct tool and a light film of assembly grease or retaining compound as the maker specifies, and support the shell squarely.
| Standard | Shell bore | Shell width | Frame type | Native spindle |
|---|---|---|---|---|
| BB86 | 41 mm | 86.5 mm | road | 24 mm (Hollowtech II) |
| BB92 | 41 mm | 91.5 mm | mountain | 24 mm (Hollowtech II) |
Figures from Park Tool and Wheels Manufacturing bottom bracket references.
Fitting a crank to a 41 mm pressfit shell?
Open the BB compatibility toolPick your shell and crank spindle to see the exact bottom bracket you need.Find BB86 BB92 pressfit bottom bracket on eBayaffiliateRelated
Sources: Park Tool: Bottom Bracket Standards · Wheels Manufacturing bottom bracket fitment reference · Bottom bracket (Wikipedia, CC BY-SA)