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Bottom Bracket Types

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Bottom Bracket Types
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There are many different types of bottom brackets available right now. From the old style ’square tapered’ spindles, external bearing bottom brackets, and press in bottom brackets, Bikeman has written up a brief description / explanation of the different styles here.

 

Contents:

Page 1 - External Thread-In Bottom Brackets (Hollowtech II, GXP, X-Type...)

Page 2 - Internal Bottom Brackets (square taper, Octalink, ISIS...)

Page 3 - Internal Press-In Bottom Brackets (BB30, BB86, BB92...)

 

 

External Thread-In Bottom Brackets:

Bearings Housed On Outside of Bottom Bracket Shell

 


TruVativ GXP

 

 

TruVativ Giga X Pipe, or "GXP" - Shop For Them Here
TruVativ crank design with a 24 to 22mm tapered spindle attached to the right (drive side) crank arm. Bottom bracket cups thread into the frame and house the bearings outside of the shell.

NOT COMPATIBLE WITH SHIMANO STYLE BOTTOM BRACKETS/CRANKS (because of taper)

 

 

 

 


TruVativ Howitzer

 

 

 

TruVativ Howitzer - Shop For Them Here
TruVativ design required for 2006 Holzfeller and Howitzer crank models - FITS NO OTHERS. 10 spline 21mm spindle and extra large cartridge bearings housed outside of the shell.

 

 

 

 

 


Shimano Hollowtech II

 

 

 

Shimano Hollowtech II - Shop For Them Here
Shimano crank design with a 24mm spindle attached to the right crank arm. Bottom bracket cups thread into the frame and house the bearings outside of the shell.

 

 

 

 

 


FSA MegaExo Light

FSA MegaExo

 

 

 

FSA Mega Exo Integrated - Shop For Them Here
FSA crank design with a 24mm spindle attached to the right crank arm. Bottom bracket cups thread into the frame and house the bearings outside of the shell. As you can see to the left, there are a few bearing variations of Mega Exo; Light, Regular, and Quad. Each works with specific cranks. See a complete FSA external bottom bracket / crank set compatibility chart here:
FSA Bottom Bracket Compatibility / PDF File (500kb)

 

 

 

FSA MegaExo Quad

 

 

 

 

 

 

 

 

 

 

 


FSA MegaExo 19

 

 

FSA Mega Exo 19 - Shop For Them Here
FSA crank design with a 19mm spindle attached to the right crank arm. Bottom bracket cups thread into the frame and house the bearings outside of the shell. See a complete FSA external bottom bracket / crank set compatibility chart here:
FSA Bottom Bracket Compatibility / PDF File (500kb)

 

 

 

 

 


Race Face X Type

 

 

 

Race Face X-Type - Shop For Them Here
Race Face crank design with a 24mm spindle attached to the left crank arm. Bottom bracket cups thread into the frame and house the bearings outside of the shell.

 

 

 

 

 

 


FSA Platinum MegaExo ISIS
FSA ISIS design that is compatible with ISIS style cranks but places bearings on outside of shell.



Internal Bottom Brackets on next page...



...Bottom Bracket Types, Continued

Contents:

Page 1 - External Thread-In Bottom Brackets (Hollowtech II, GXP, X-Type...)

Page 2 - Internal Bottom Brackets (square taper, Octalink, ISIS...)

Page 3 - Internal Press-In Bottom Brackets (BB30, BB86, BB92...)

 


Internal Bottom Brackets:

Bearings Housed On Inside Of Bottom Bracket Shell

 


 

ISIS Spline

 

 

ISIS - Shop For Them Here
10 spline, 21mm spindle. Compatible with any crank designed to be used with an ISIS bb, regardless of brand. Not Shimano compatible.

 

 

 

 

 


 

TruVativ PowerSpline



TruVativ Power Spline - Shop For Them Here
TruVativ design fits only TruVativ cranks designated as Power Spline compatible.

 

 

 

 

 

 


 

Octalink V1 Spline

 

 

 

Shimano Octalink V1 - Shop For Them Here
Original Shimano 8-spline pipe spindle. For Dura Ace 7700, Ultegra 6500, 105 5500, and XTR 950-952 cranks.

 

 

 

 

 


Octalink V2 Spline

 


Shimano Octalink V2 - Shop For Them Here
Shimano 8-spline. Fits following crank models: XT M751-752, LX M571-572, Deore M510-8, M445 and M440-8.

 

 

 

 

 


 

JIS Square Taper (Shimano)ISO Square Taper (Campagnolo)


ISO and JIS Square Taper - Shop For Them Here
The bottom bracket design that fit most cranks from 2000 and earlier. Two major styles of square taper bottom brackets are:

1. Japanese International Standard "JIS" (Shimano compatible)
2. International Organization for Standardization "ISO" (Campy)

While both use a 2 degree taper, the Campy (ISO) spindle starts and finishes smaller than a Shimano (JIS). Therefore, the JIS and ISO bottom brackets are not compatible with each other and must be matched with a compatible crank or you risk damaging the crank arm.

 


 

Internal Press-In Bottom Brackets on next page...



...Bottom Bracket Types, Continued

Contents:

Page 1 - External Thread-In Bottom Brackets (Hollowtech II, GXP, X-Type...)

Page 2 - Internal Bottom Brackets (square taper, Octalink, ISIS...)

Page 3 - Internal Press-In Bottom Brackets (BB30, BB86, BB92...)

 

Internal Press-In Bottom Brackets:

Bearings Pressed Inside of Bottom Bracket Shell

 

All of the previously mentioned bottom brackets house bearings in a cup or shell which is then screwed into the shell of the frame. The newest style of bottom brackets dispense of that threaded bearing cup and have the bearings pressed directly into the frame, sometimes without a cup of any sort. There are many excellent reviews and discussions out there on the old inter-webs about the pluses and minuses of the different systems (eg, stiffness, q-factor, compatibility) and their origins but I plan to keep it real simple here.

 


 

BB30 - Shop For Them Here

The '30' in BB30 refers to the diameter of the crank spindle.

Bearing with a 42mm outside diameter (OD) and a 30mm inside diameter (ID) drop directly into compatible frame shell. A c-clip creates a shelf that the bearing sits up against.  Crank uses 30mm spindle. BB30 frames can utilize either a 68 or 73mm width shell, generally road or mountain, respectively.

At the time of writing there is no Shimano crank that is BB30 compatible nor will there be anytime soon. However, BB30 bottom brackets can be adapted to accept some non-BB30 cranks, for example, Shimano Hollowtech II or TruVativ GXP. See some adapters HERE. Other adaptations may be available, call us for your specific questions or needs.

==================

PressFit 30

PressFit30 (PFBB30) -

Same as BB30 above except the bearings are housed in a cup that is pressed into the frame. PressFit30 frame bottom bracket shells have a larger ID than BB30 in order to accept the larger bearing/cup.  PressFit 30 frame bottom bracket shell ID (or the bearing's OD) is 46mm vs 42mm on a BB30 frame.

PressFit 30 systems use the same crank as BB30.

There are adapters to convert PressFit 30 frame shells to accept non-BB30 cranks, call us for current options depending on your needs.

 


BB86

BB86/BB91 - Shop For Them Here

The number in BB86 or BB91 refers to the shell width of the frame, generally road and mountain, respectively. This standard was introduced by Shimano and involve bearings pressed into cups that are pressed into the frame. These utilize cranks with 24mm bottom bracket spindles and use the same bearing OD/ID dimensions as are found in external cup bottom brackets (Hollowtech II, MegaExo).

It might help to think of it this way - When you take a traditional 68 or 73mm threaded bottom bracket shell and thread in external bearing cups (Like Shimano HollowTech,

==================

BB90

BB90/BB95 -

This system is used by Trek and is similar in design to the BB86/91 systems above but there is no bearing cup, the bearing sets directly into the frame. Uses crank with 24mm spindle.

 

 


 

BB386 EVO -

A system designed by BH Bikes collaboration with FSA.  This system uses a very similar bearing and cup as PressFit 30 but it is placed the same width as the BB86 system.  The system is intended for road only because of the large size of the cup needed to fit the bearing and the wide width it is placed at (the large width and diameter of BB386 EVO on a mountain bike could interfere with using a granny gear and could interfere with pivot placements on full suspension bikes).

 


Comments (1)add
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BB adapter
written by Chris Choi , April 21, 2012
Hi,
I'm building up a 2011 Wilier Cento1 and I'm not very certain which adapter I would need to use if I were to use a Dura Ace 7900. Can you help? Thx...
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