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At the 2011 Interbike show, Calvin Jones of Park Tool sighed as he described the proliferation of new bottom-bracket dimensions. I've covered all the ones here which I can find, and listed them in order of bottom-bracket shell internal bearing seat diameter so as to highlight compatibilities. Adapters for some -- ranging from the venerable Ashtabula system to new high-end systems -- allow use with a variety of spindles. Phil Wood makes adapters to fit most press-fit bottom brackets: "[i]f you have a press fit bottom bracket (Merlin, Klein, Fisher, Ritchey, Fat Chance) and need replacement parts, we have spindles and bearings that will work" -- see Phil Wood FAQ page on bottom brackets. Wheels Manufacturing makes a number of adapters between these systems, as does FSA. Also see compatibility information in the table below . -- John Allen.
|Standard:||Threading or press fit||Adjustable
|Merlin||30 mm pressed||68 mm|
|Thompson/Thun||30, 33, 35, 40, 45 mm pressed||left (cone and locknut)||right (cone and locknut)||65, 68,70 mm||2-piece or 3-piece crank. Sup and cone bearings. No shoulder inside shell; loose tolerances.|
|Mavic/Stronglight||1.375" (or 35 mm) beveled||65-73 mm||Bottom bracket cartridge clamps into a conventional BB shell once the ends have been faced with a 45-degree taper. Can work with English, ISO, French or Raleigh. Italian?|
|Velo Orange threadless||1.375" (or 35 mm), threaded or unthreaded w/o shoulders||68 mm||Clamps into bottom-bracket shell using expanding sleeves. but not Italian threaded BB shell unless possibly with a steel shim, 0.20"/0.5mm|
|Fat Chance/Gary Fisher||35 mm pressed||68 or 73 mm||Circlips on grooves in axle outboard of bearings|
|Klein||35 mm pressed||68 mm|
|Ritchey||35 mm pressed||68 mm|
|Shimano Hollowtech II, FSA MegaExo, RaceFace X-type||37 mm pressed or British/ISO threaded||l||90 mm, 95 mm including cups||External cups for cartridge bearings fit British/ISO threaded bottom brackets or unthreaded shell. 24 mm spindle, spacer to use 6805 bearings with 25mm I.D.. Bottom bracket shell must be faced so cups are parallel.|
|BB90/BB95||37 mm||90 mm, 95 mm||Used on Trek Madone carbon frames. 24 mm spindle.|
|BB83/BB86, BB92||41 mm press fit||86 mm||19 mm or 24 mm spindle|
|BB30, Cannondale System Integration||42 mm press fit||68, 73 mm||Adapters allow use with various 30 mm spindles.|
|Specialized OSBB Aluminum||42 mm||68mm||See compatibility guide. Usable with several BB30 spindles with Wheels Mfg. adapters|
|Roadmaster child's||43 mm||65 mm|
|Specialized OSBB Carbon||46 mm||61 mm||See compatibility guide. Adapters increase shell width to 68 mm. Usable with several BB30 spindles with Wheels Mfg. adapters|
|Pressfit 30 (PF30)||46mm slip fit||68, 73 mm||30 mm OD spindle; plastic retainer for cartridges.|
|Cervelo BBright||46 mm||80 mm||Adapters allow use of various spindles.|
|BB386EVO||46 mm press fit||86.5 mm||Like PF30 but wider and with press-fit bearings. See info on FSA Web site.|
|ISIS Megatech||48 mm pressed||68 mm|
|FSA Megatech||50 mm pressed||68, 73, 83 mm|
51.3 mm (2.02") i.d.
|left (cone and locknut)||right (cone and locknut)||
68 mm (2.68") wide
| Older U.S. bikes, BMX, Juvenile bikes,
Department store bikes.
24 tpi cranks use #66 retainers, with 10 5/16" balls.
28 tpi cranks use #64 retainers, with 9 5/16" balls.
Note: Some higher quality(mostly BMX) bikes used Tange 24 tpi bottom brackets with #64 retainers.
|Eccentric||54 mm||68 mm||For tandems and single-sprocket drive with vertical dropouts or belt drive. May be split with pinch bolts, or have setscrews. Shell diameter not critical. Also see Gary Fisher Eccentric below.|
|Gary Fisher Eccentric||57 mm||73 mm||Also see Eccentric above.|
|Articles by Sheldon Brown and others|
Last Updated: by Harriet Fell