Bottom bracket compatibility - what can be combined with what

Compatibility [10] Bottom brackets

Updated: 16/11/2018.

This post will explain bottom bracket compatibility. Which bottom brackets (BBs) can be combined with which crankset standards.

Posts that explain in detail the history and construction of each BB standard can be found here:
1 History and threaded BB standards
2 Threadless (press fit) bb standards
T47 – a new threaded BB standard

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.

1. Compatibility of bottom brackets

Table of BB standard and compatible cranksets of different standard (all the BBs accept the same standard cranksets, of course, others require an adapter, as is explained in chapter 3):

BB standardCrankset compatibility
Threaded (brit, ital.)square tapper, ISIS, Octalink, Hollowtech II, BB386EVO
The first 3 require BB cartridge of their standard to be installed. HTII and BB386EVO require HTII BB shell
1 a) BB30Hollowtech II, BB386EVO,
1 b) BB30AHollowtech II, BB386EVO, BBright, BB30 if they have spacers on the left side
2. PF30, OSBBHollowtech II, BB386EVO, OSBB, BBright, BB30
3. BB86, BB90, BB92Hollowtech II
4. BBrightHollowtech II, BB386EVO
5. BB386EVOHollowtech II, BBright, OSBB, BB30 if the spindle is long enough
6. BB90, BB95Hollowtech II
7. PF86, PF92Hollowtech II, BB386EVO
   T47All – if the spindle length is appropriate

2. Compatibility of cranksets and different BBs

Table of crankset standards and compatible BBs (all the cranksets are compatible with the BBs of the same standard, of course, the others needing a special adapter):

Crankset standardBB compatibility
Square tapperThreaded (british, italian)
OctalinkThreaded (british, italian)
ISISThreaded (british, italian)
Hollowtech IIThreaded (british, italian), BB30, BB30A, PF30, OSBB, BB86, BB90, BB92, BB95, BBright, BB386EVO,
BB30PF30, OSBB, BB386EVO if it matches the spindle length, BB30A if the crankset has spacers on the left side
BB30ABB30 with use of spacers on the crankset
PF30/
OSBBBB386EVO
BB86, BB90, BB92/
BBrightBB30A, PF30, OSBB, BB386EVO
BB386EVOThreaded (british, italian) with Hollowtech II BB, BB30, BB30A, PF30, OSBB, BBright, PF86, PF92
BB90, BB95/
PF86, PF92/
T47Fits all the BBs – if the spindle length and diameter match the required for the BB used

3. Combining different standards

There are several adapters made by various independent manufacturers that can match certain BB standards with certain crankset standards. They are usually placed directly into the frame, replacing the “standard” BB bearings. Solutions vary from case to case.

Praxis Works' adapter to fit 24 mm spindle diameter cranksets in a PF30 compatible frame cartridge shell.
Praxis Works’ adapter to fit 24 mm spindle diameter cranksets in a PF30 compatible frame cartridge shell.
Clicking on the image opens Amazon affiliate link with a bottom bracked adapter search.

Amazon.com search of bottom bracket adapters (as an Amazon Associate, I earn from qualifying purchases).

4. What to pay attention to when buying bicycle, cranksets, or BBs?

In terms of both BBs and cranksets, of course. There are so many (in)compatible standards and how not to get confused or get mismatching equipment? Just follow these simple steps:

  1. Always check for the frame you have, or are planning to buy, what standard of BB does it’s BB shell have. Pay attention to all the details.
  2. If buying a BB, make sure it fits the frame BB shell (as determined in step 1).
  3. If changing cranksets
    BB30 and PF30 cranksets won’t fit frames with different BB shell standard, because their spindle will be too short.
    Cranksets with 30 mm wide spindles won’t fit into frames with BB86, or BB90 BBs, but with correct BB some can be made to fit into threaded frames.
    Cranksets with 24 mm spindle diameter are the most versatile and, with the right BB, or adapters, can fit almost any frame.
  4. 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.
  5. If the frame has a press-fit BB shell (without threads, threadless), then you need quite expensive, special tools to install and remove/change BBs. If not using such tools (like a bearing press), bicycle frame can be damaged.
    On the other hand, threaded BBs allow the use of simple, inexpensive tools.
  6. When it is all set up correctly, differences between different BBs (e.g. stifness) are never perceivable when riding the bike – basically they are unimportant. So there is really no need to buy a frame with a certain BB standard because it is marketed as stiffer, better. Just see what kind of frame you like, or what components you already have, and go for the simplest, easiest, cheapest solution to make it all work.

5. Author’s personal opinion

For ease of installation and replacement, threaded BBs rule!  🙂

Square tapper and Octalink BBs are by far the most durable, long lasting ones.

New T47 standard looks promising, but still not enough first hand experience data to confirm durability and ease of maintenance.

 

Related post – Bicycle cranks (“crankset”) compatibility:

Bicycle crankset compatibility (cranks, chainrings)
Bicycle crankset compatibility

 

Compatibility posts are also available in eBook (printable and Kindle) and paperback editions on Amazon:

Bicycle Drivetrain Compatibility on Amazon
Bicycle Drivetrain Compatibility on Amazon
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2 thoughts on “Compatibility [10] Bottom brackets”

  1. Hi does anyone know what cranksets will fit a shimano BB70 bottom bracket please. Im really stuck in finding information that will help me decide what cranks to buy.

    Reply
    • That is Hollowtech II BB, right?

      In that case, the options are:
      – Square taper BB installation and square taper cranks.
      – Octalink BB installation and Octalink cranks.
      – Hollowtech II (as the noted BB70) BB and cranks with a spindle width of 24 mm, including of course the Hollowtech II cranks.
      – Special BB that allows for 30 mm wide spindle to use with BB386EVO and BB392EVO.

      So, in addition to the above noted, cranks that can fit are:
      Race Face X-type, FSA MegaEXO, Truvativ/SRAM Giga X Pipe (GXP), Campagnolo Ultra Torque.
      – As long as a compatible BB cartridge is used.

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