Cranksets with 24 mm spindle diameter are not all the same! SRAM and some other manufacturers make spindles that are 24 mm wide at one end, and 22 mm wide on the other, so the correct matching BB needs to be acquired. Cons: Heavier than press-fit systems; frame design limited by relatively small-diameter and narrow shell Threadfit 82.5 is not really a new standard in that it is compatible with BB86 cranksets and bearings.

The tolerances are not too different but the way they’re measured is. They both have the same needs for concentricity and placement relative to the frame. The threads are at a disadvantage in that they need to be machined from both sides and have a hard time sharing a centerline, whereas our OSBB is machined from one side all at once — and round holes are easy to measure.”However Shimano advertise that SM-BBR60 & BB-R9100 use 'small ball bearings'. This is not necessarily a good thing, in that smaller bearings are weaker. However there are more of them. Still it would be reasonable to assume that the RS500 will be DIFFERENT in durability from the other two, but not necessarily worse. Crank designs that will fit: Standard 24mm external type (Shimano Hollowtech II, SRAM GXP, Campagnolo Ultratorque and Powertorque, FSA MegaExo, Race Face X-Type, etc), square taper, ISIS, BB386EVO, BB392EVO many others. Crucially external cups that fit 30mm spindles do exist. Note: crankset for mounting on externally screwed in bearings, with a hollow axle 24 mm in diameter, is compatible whichever manufacturer produces it. So: Race Face X-type, FSA MegaEXO, Truvativ/SRAM Giga X Pipe (GXP), Campagnolo Ultra Torque – they are all compatible with Shimano Hollowtech II standard, so only Hollowtech II will be named in tables and remainder of the post. Scott US marketing and PR director Adrian Montgomery touts similar reasons for his company choosing BB86/92 over other standards:

Crank designs that will fit: BB30, BB386 EVO, standard 24mm external-type, Specialized OSBB, BBRight. Can be adapted to almost any standard with suitable adapters. Most of the Shimano Hollowtech 2 BBs are lightweight models to begin with, so there is not much of a weight difference. Crank compatibility is another BB386 EVO strongpoint. Despite the bulbous dimensions, the shell will accept most modern crankset fitments save for dedicated BB30/PF30 and BBRight designs. If you have any questions (or additions and corrections), please use the BikeGremlin forum’s compatibility section: Because the crank arms are straighter, we can make them lighter than BB30 ones,” he says. “But because the BB386 EVO spindles are longer than BB30 ones, they aren’t as stiff. Total stiffness is not a measure of crank stiffness alone, though. When you factor in the stiffness gains from a wider shell, the overall stiffness will be highest when BB386 EVO frames meet BB386 EVO cranks.”With the PressFit 30, they’re using the same technology with the larger bearings and the same technology with the bearings living inside the frame, but they’re utilizing the nylon to their advantage where you have a more realistic tolerance.” Our] Hollowgram SiSL2 crank with SpideRing weighs 484g. By comparison, Dura-Ace 9000 weighs around 678g [we recorded 637g in our review – ed]. In addition to weight, another BB30 advantage is stiffness. By increasing the spindle diameter, you increase its resistance to twisting, which is where the bulk of the deflection in a crankset comes from. Roughly 70% of total deflection measured at the pedal comes from axle twist.”

Once you’ve narrowed down your search by “mounting standard,” the last thing to consider is weight, color, and grade.

Why are there so many bottom bracket standards?

At this point, your choices will be quite limited. Weight, Color, and Grade are the Final Deciding Factors BB30 and PF30 cranksets won’t fit frames with different BB shell standard, because their spindle will be too short. Very closely related to Trek’s BB90/BB95 system is the BB86/BB92 standard used by Scott, Giant, Pivot, and many others. The idea is simple, by moving the bearings outboard of the shell, you can then use a much larger spindle. Currently, 24mm is the accepted norm compared to square-taper’s relatively minuscule 17mm diameter. Cons: Same as BB90/95 in theory, but in practice there are generally less issues experienced due to the less stringent tolerances