08 Dec Redefining “standard”

So it used to be that bikes had 68mm or 73mm wide bottom bracket shells. I know there were other standard before that, and Italian threaded bb’s rear their ugly head from time to time, but for the most part, there were two “standard” sizes.

In the past couple years though, things have gotten a little stupid. With the proprietorizing of components that the big manufacturers seem so fond of these days, us lucky wrenches get to deal with the following ridiculousness soon:

Here is a quick guide to a number of these new standards:

BB30, or 30 X 68 and 30 X 73mm bottom brackets, come in either 68mm or 73mm shell widths for road or mountain bikes. The spindle diameter is 30mm, and the 41mm-diameter bearings press straight into the BB shell and are held in place by snaprings. In addition to Cannondale (who named the system) and Specialized (which doesn’t call its system BB30), FSA and SRAM (TruVativ) make BB30 cranksets; Shimano does not, and Campagnolo makes press-in adaptor cups to fit its Ultra-Torque (and Fulcrum Racing-Torq) cranks to a BB30 shell.

Scott and Shimano came up with BB83/BB86, often called the “Shimano system,” but not by Shimano. It accepts a standard 24 X 90mm road or 24 X 95mm MTB crank spindle. The shell is 86.5mm wide with a 41mm ID. The bearing has a 37mm OD and is pressed into a nylon insert with a 41mm OD that presses into the frame . Each insert’s shoulder is 1.75mm wide, creating the 90mm width and hence the BB90 name. Shimano, FSA and SRAM offer BBs to fit this shell; Campagnolo makes press-in adaptor cups to fit its Ultra-Torque (and Fulcrum Racing-Torq) cranks to BB83/BB86 shells.

BB92 is the MTB version of the BB83/BB86 with a 91.5mm wide shell for MTB triple cranks. Again, the 3.5mm of the two shoulders add width to 95mm.

BB90 is Trek’s Campy- (and Shimano-, SRAM-, FSA-) compatible Madone system. The BB shell is 90mm wide by 37mm ID. The 37mm OD bearings (the same bearings as inside an external-bearing cup) insert directly into the carbon frame and accept integrated-spindle cranks.

BB95 is the MTB version of BB90 with a 95mm wide shell on the new Trek Top Fuel and Fuel EX carbon.

Wilier’s new system has a 94mm wide BB into which a Campagnolo Ultra-Torque (or Fulcrum Racing-Torq) crankset fits directly without cups or retaining clip.

Lifted entirely from Velonews, courtesy of Lennard Zinn. Isn’t that nice and straight forward for you. Odd of any old shop having the bearings/bb you need for the proprietary setup on your new Madone when you are on a road trip? Probably not too good.
I came across this just now, and hadn’t realized how ridiculous this had gotten. How many of these new systems do you think will be around in ten years? Gonna be easy to replace that crank?
I better be careful, I’m going to start approaching “crusty old bike mechanic” status.