You know what makes bad design? You do. It’s something that you use that consistently fails to do it’s job. Or, in doing the job poorly, draws attention to it doing a botch job. Bad design is something that makes you angry, because it refuses to let you ignore it. Having worked around bikes a hot minute, I’ve seen plenty of bogus design approaches on the bike. I’ve seen everything from construction materials obviously inferior in quality to the demands of use or bogus little cable routings to make sure that you can’t see a 10cm stretch of housing at the cost of garbage shifting. And I haven’t started on shifter and derailleur compatibilities.
No. What I’m really interested in talking about today is one particular part. It’s small. It’s plastic. And it is the dumbest “clever” workaround to an actual engineering dilemma: the SRAM Force 22 BB30 bearing preload spacer. That’s right, a two-for-one crack at two pretty simple problems, spacing and compression.
In part, the industry is to blame. Over the past 30 years the whole weight of high-end tech has been pushing the envelope of bike design (for pro riders) and carving out a whole new way of convincing people that spending as much on a top-of-the-line bike as a new 4-door sedan is not an insane proposition. This also means developing a wide range of wildly proprietary new size standards, easy to break bits-and-bobs, and reintroducing components that many mechanics had believed to be extinct. This includes the like the C-clip (more lovingly knowing as the Jesus Christ clip because when the thing invariably flies off during a repair and is lost the first words out of your mouth are “Jesus Christ!”).
But back to the my beloved BB30 bearing preload spacer. It’s the bastard offspring of a generally rash and ugly effort to improve power transfer via the crank/BB interface (oh so important). For millennia (in bike tech terms) many a mechanic reveled in the peace brought by the general adoption of the English standard threaded 68mm bottom bracket. It even adapted well and accommodated stiffer and lighter through axle cranksets partnered with a bearing that mounted outboard of the BB shell. All was well.
Then some horrible twisted engineer came up with the idea of throwing a wrench in everything and returning BB standards to the dark ages. BB30 itself is kind of dumb. Manufacturers tout the material benefits of using aluminum alloy for through axle cranks because it’s stiffer and it’s marginally lighter too! But at the standard torques people push there’s not much in it for the average joe, nor is it much lighter because for the diameter the aluminum has to be pretty thick.
BB30 also regularly features a variety of different widths, depending on the make of the frame. Most common, BB30 utilize press fit bearings. Like the kind you had on that old Schwinn with the one piece crank. You know, the one you pulled out of the garbage bin behind Goodwill. Oftentimes these outfits are finicky and require regular adjustment, even then they tend to just be noisy. Because it’s not important to consider noise when we’re talking about the one part you never stop applying force to in a regular motion. Assembly manuals also will call for use of a hammer or Loctite (Loctite!) for proper installation or maintenance.
Then there’s brilliant little brainfart innovations such as the preload spacer used in SRAMs line that just leaves me applauding. The documentation is all there. It’s an ingenious development; A shift from the treacherous wave washer used to provide lateral compression on the BB30 bearings of yore (simply, to keep your BB from squeaking).
It’s stupid. I get mad just thinking about how stupid it is. It’s a solution to solve a problem offered by a previous bad solution. It hasn’t effectively addressed the problem: spacing and compression. I just don’t understand (well I do, but in short it’s money and that’s not a fun answer) how the pre-existing solution for this problem, i.e. using a compression cap screw and clamp screws to affix the crank to the axle and put the proper preload on the bearings, isn’t used.
I’ve read up on it a bunch, because I am a confident mechanic but try to remain humble when facing new problems. And I have this to say: After installing it and adjusting it time and time again to be re-greeted with the same groan after a few days in the saddle, my tolerance is gone. This thing sucks. I suppose there’ll always be the argument from the vested engineer “that if you install everything correctly and just right it will never pose a problem”, but that argument can kiss my ass. What’s more important? Fixing a problem or fixing the thing that’s supposed to fix the problem?