by Clint
Modern bottom brackets are classified in three different ways: Shell interface, shell width, and spline. Shell interface and width are dependent on your frame while spline is dependent on your crank. All of our frames are English threaded. The Campeur, Pass Hunter, Polyvalent, and Camargue all use the standard road shell width of 68mm. The Piolet uses a 73mm shell to allow for larger tire clearances and mountain components. All of our cranks are JIS square tapered.
Besides the standard English threading, and other nationality based threading patterns (discussed in the previous post), other shell interfaces include:
-336EVO - 46mm diameter, 87mm width
-BB30 - 42mm diameter shell
-BB86 - 41mm diameter shell, road bikes
-BB89.5 - 41mm diameter shell, 89.5mm width
-BB90 - Trek, bearing cartridges sit directly in frame
-BB92 - 41mm diameter shell, mountain bikes
-BB95 - Trek, bearing cartridges sit directly in frame
-BB107 - 41mm diameter shell, 107mm width
-BB121 - 41mm diameter shell, fat bikes
-BBright Direct fit - Cervelo, offset from the center plane, 79mm wide, 42mm diameter
-BBright Press fit - Cervelo, offset from the center plane, 79mm wide, 46mm diameter
-PF30 - 46mm diameter shell
-PF41 - 41mm diameter shell
Please note: in the BB# naming system, the # can refer to the spindle diameter, shell diameter, or shell width.
All of these are threadless, but that doesn't mean they're compatible with our threadless bottom bracket. Most are wider shells for larger spindles and bigger bearings. Threadless shells have been around for a while. Merlin frames had their own threadless shell.
You can try the new T47 standard if you want the advantages of a large diameter, but without the creaking and noise associated with threadless shells. According to press releases, the T47 should "yield a much higher interface success rate."
Bottom bracket shell widths range anywhere from 61 to 132mm. The wider stuff is generally for fatbikes and larger tire clearances. Getting a drivetrain to clear those large tires has been a challenge in the bike industry lately. The solution is usually a combination of thiner chainstay, wider bottom bracket, wider rear, and larger Q factor.
Last is the spindle interface. A few of these include:
-386 EVO - like BB30 but requires a longer spindle
-BB30/PF30 - 30mm diameter spindle
-BBright - crank must accomodate offset
-Campagnolo Power Torque - outdated Campy system
-Campagnolo Ultra Torque - current Campy system
-FSA Mega Exo - downhill, extra bearings, there are several versions of this system
-Hive Polygon - it's not a polygon, it's a rounded triangle
-ISIS - it came out before the other ISIS went mainstream
-RaceFace Cinch 30mm - oversize spindle
-Rotor 3D+ - oversize spindle
-Shimano Hollowtech II - current Shimano standard
-Shimano Octalink VI - no longer used for cranks, but I think you can still get bottom brackets
-Shimano Octalink V2 - same deal, replaced by Hollowtech
-TruVativ GXP - SRAM for 2 piece cranks
-TruVativ Howitzer - oversized for downhill
-TruVativ HammerSchmidt - HammerSchmidt was revolutionary
-TruVativ Power Spline - functionally similar to a square taper but with a proprietary spline
-Zipp Vuma - I think this is some kind of aerobics class
The ones you should know (besides square taper) are Shimano Hollowtech II and Campagnolo Ultra Torque. Hollowtech II is compatible with some other stuff. For example, newer models of the FSA Gossamer crank can use a Shimano Ultegra Hollowtech II bottom bracket. I have this on my cross bike. Campagnolo Ultra Torque is certainly less common (if not exclusive to Campagnolo cranks), but new Campy is still cool. Everything else is garbage.
Some other bottom brackets standards and technologies not discussed in this post include
-BB7 - these are brakes
-BB8 - this is a robot
-BMX - designed for impact and stunts
-CF69 - I made this up
-Eccentric - they're a bit off center
-Freewheel - featured on some old Schwinns
-Tandem - usually eccentric
Some of the new bottom brackets have their advantages. Some introduce new problems. Most are designed for stiffness. Maybe someday we'll change, but the square tapers still work.
Posts
8 comments:
No love for GXP?! GXP is probably my favorite, as far as 2-piece cranksets go, as it is pretty much idiot-proof. I believe that GXP works in a similar fashion to Campy's Ultra Torque (no pre-load bolt) but I could be wrong as I've not had my Athena crankset off in a while.
Thanks for the humorous post!
What about Selecta and the correlated Front Freewheel System? =)
Joking aside, Octalink was actually a decent interface (and better than ISIS afaik), and it performed as well as Square-Taper but with a possible hollow axle. Too bad Shimano didn't want other people using it.
Power-Torque isn't outdated, it's the current standard for Athena, Potenza, Centaur and Veloce. Instead of two half-axles and bearings pressed onto each crankarm, it's a single axle and pressed bearing on the drive side crankarm; versus a fixing bolt and spline, with a bearing in the cup on the non-drive side.
Hear about the new one, BB420? Means you must be high if you think we need yet another new bottom bracket standard! Seriously, one I worry about is Truvativ's "power spline;" it looks like a stripped crank arm waiting to happen.
+1 for "everything else is garbage". Especially FSA. I sometimes offer Shimano Hollowtech II cups as an upgrade for customers riding on FSA cranks/BBs, which are notorious for having extremely short bearing life. I've found lots of FSA cranks are compatible with the much better Shimano cups - some spacers here and there may be necessary.
These were nice posts. How about a similar series on headsets?
And while I'm at it, does anyone else wish someone (like VO) would make a modern threadless 1-1/8" headset with roller bearings readily available. I get all kinds of shimmy on my low-trail Rawland Nordavinden, and I've heard this might help.
And what about this T47 BB standard, sounds like it could be a winner (if large diameter tubes actually bring something to a steel bike that is)?
a few good things to note when buying cranks.
1.a BB30 crank has a 30mm diameter spindle and was originally a sram design for pressfit frames. blame your woes on them.
2. GXP is srams spindle spec for threaded bb shells. most their crank sets come in both standards (on a gxp crank the spindle tapers from 24/22mm diameter, shimanos hollowtechII is 24mm throughout and the dictation of it beloning to a road or mountain group will tell you if the spindle will fit a 68mm shell or a 73mm shell)
*personally I like to attribute our refusal to label spindle widths to the lack of standards
3. bb386 is a spindle standard designed by FSA (basically their answer to srams bb30). and like a BB30 crank it has a 30mm spindle diameter but has a wider spindle which allows for 30mm cups to be threaded into a 68mm threaded frame. (the wider spindle allows you to account for the space the cups will take up on the outside of the frame 68mm+X because bb shells exceed a 30mm ID
so next time someone tells you that you can fit a bb30 crank in an English frame you'll know why :)
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