When the BB386EVO standard was introduced with the BH Ultralight, we could almost hear the collective sigh around another standard. But on paper, it offers a lot of flexibility in its implementation and does allow frame manufacturers some impressive additional real estate at the bottom bracket shell.
While building up our Project MonsterCross bike, we started talking to FSA in more depth about the standard and how it can be used on non-386EVO frames. And, for that matter, why you’d even want to use it on a non-386EVO frame…
Shown here are two FSA SL-K Light compact 110 BCD cranksets with 175mm arms. The one with black rings and silver spindle is a BB30 crankset (with 36/46 cyclocross rings). The other is BB386EVO with 34/50 compact rings. FSA gave the EVO spindle a gold hue simply for visual differentiation, making it quick and easy to identify which is which.
BB30 and Pressfit BB30 are based on a 68mm wide bottom bracket shell. BB386EVO has an 18.5mm longer spindle designed around an 86.5mm wide BB shell. The full spindle length obviously includes the space for the non-drive crank arm to mount and a wave spring that maintains proper bearing load.
Because the EVO BB shell is wider, the arms must have less curvature. From FSA:
“Q-Factor is 146mm on both, the same as our BB30 and MegaExo cranks. In order to maintain that Q-Factor, we use slightly less arm curvature than a BB30 crank, but were still able to keep more than our MegaExo cranks. Ankle clearance can be a concern for some riders with excessive foot angle on the down stroke, but the curvature of the 386 EVO arms is at least as good, or better than industry standards.”
From the side, the cranks have a different profile. The EVO cranks (top) are a little more shapely with a bit of a bulge on the trailing edge at the pedal hole. FSA’s Matt VanEnkevort says it’s really just cosmetic, but gives it a “faster, more aggro look.”
So it looks good, but is that all? Nope. The EVO crankarms are lighter and stiffer:
“There’s less material because it doesn’t have as much curvature, and a straighter arm is going to be stiffer,” VanEnkevort said. “It’s possible, and we haven’t tested this, but it’s possible that an EVO crankset might even be slightly stiffer (than the BB30 setup) in a BB30 frame.”
Even with the larger overall set of rings and longer spindle, the EVO driveside parts are only 16g heavier. Take the 10g savings from the non-drive arm and we’re betting you’d come out just a bit lighter with the same chainring combo on each.
Just for fun, there’s a 4g difference between standard (left) and ceramic bearing PFBB30 bottom brackets.
Question is, if you have a BB30 or PFBB30 frame, is there any reason to consider the wider BB386EVO cranks? Probably not, but:
“If you have a BB30 frame, the best solution is a straight up BB30 crankset,” says VanEnkevort. “The EVO advantage really comes when you have a frame with the wider, stiffer bottom bracket or for someone who’s either transferring it between EVO and BB30 frames or planning on upgrading their frame in the future.”
If you do decide to run an EVO crankset on a BB30/PFBB30 frame, FSA offers simple spacers to fill the gap between the bottom bracket bearings and the crankarms.
For the Pressfit bottom brackets, the ones shown above are the same for either standard PFBB30 frames or EVO frames. The gray plastic shell between bearing cups slides open enough to accommodate the wider EVO frames, too.
GOING OFF BRAND:
The flip side is fitting a BB386EVO frames with other cranksets. While FSA was one of the original partners in developing the BB386EVO standard, they’re working on adapters for SRAM’s tapered GXP spindles and, eventually, Campagnolo’s UltraTorque cranksets, too. VanEnkevort says the Campy adapters require a bit more engineering to properly incorporate the retention rings necessary thanks to their split spindle design.
Shimano has had PFBB86 cranks for a while, but they use their standard 24mm diameter spindles. All that’s needed to run those cranks on an EVO frame is a reducer between the 30mm ID of the bearings and the 24mm OD of the spindle. FSA’s adapters (above) reduce BB30 down to 24mm ID for use with their MegaExo cranksets. Despite minute (we’re talking two spots right of the decimal) differences in actual spindle diameters between their MegaExo and Shimano cranks, FSA says these will work. We’ll test this in the near future. (FSA’s MegaExo is their outboard bearing setup)
And as a final word about the “new standard”, if you really think about it, BB386EVO is simply taking Shimano’s and Campy’s existing press fit 86mm standard and giving it the popular 30mm diameter spindle. Not exactly groundbreaking when you think of it that way, just sort of a natural evolution.