Oh sure there’s a benefit to imposing some rigour into the process of producing bike parts. Making Part A fit with Part B, regardless of manufacturer is a Good Thing in my book, but the history of the frame/crank interface is littered with ever-changing designs with varying degrees of engineering integrity.
Just from my own experience, there’s the good old square taper bottom bracket, a design that was heavy, lasted for ages but suffered from cranks seizing on. Next came the notorious ISIS bottom bracket, a name that today is unlikely to ever get past a marketer’s initial brain-fart. Or an engineers either, unless the idea was to produce something that lasted five minutes and needed constant replacement.
After that, Shimano nailed it with Hollotech. End of story really, unless you were SRAM who have never been keen to pay royalties unless they have to. So they came up with GXP – basically, same, but different. Again, a reasonable, reliable design but with an inherent inferiority in axle diameter. Not much, but enough.
So, then came various oversized efforts – BB30 pressed directly into the frame which allowed up to 30mm axles, followed by Press Fit efforts – PF30, PF92 and other variations on a theme to try and engineer out bottom bracket variability in frame manufacture. Often creaky, rarely beneficial they had strong axles but a tendency to fail due to relatively limited space for bearings and seals. Oh and don’t forget the intriguing but weird e-thirteen triangular crank interface that is 30mm but not BB/PF30…
There are others that I haven’t listed but you get the idea. No-one makes us use this stuff but if you buy a bike with a certain type of bottom bracket, and it turns out you’ve backed the wrong horse on an otherwise great bike, then tough luck.
This sort of thing annoys consumers though.
Now SRAM has introduced another standard with it’s new bottom brackets. They have produced bottom brackets that take a… 28.99mm axle diameter and dubbed it (sorry) DUB – Durable, Unified Bottom Bracket. Which obviously need DUB compatible cranksets to go with them. The reasoning is to free up space for bigger bearings and better seals (both good), while getting almost but not quite to 30mm axles for stiffness. The claim, is lower weight and better reliability. Which I have heard before.
To be fair, the cranks available (and SRAM have brought out a whole slew of cranks) are very light – just 420g for a SRAM XX1 Eagle DUB SL at the top end (with bottom brackets that range in weight from 71g to 89g). That’s lighter than the Race Face Next SL, but you know, marginal gains. At the other end of the scale, a Stylo or Descendent will tip the scales around 717g with steel chainrings.
So there you go. This looks a worthwhile improvement- new supposedly reliable bottom brackets for almost everyone, and SRAM cranks for every pocket. It’s unlikely that Shimano will ever produce 28.99mm diameter axles for their cranks, but everyone else can reasonably be expected to move in this direction over the next couple of years.
And SRAM’s stranglehold over the big S appears to have tightened that little bit further.