I have a Campy Ekar drivetrain on my gravel bike, and while I’m mostly happy with it, I feel like there’s an issue with the bottom bracket that’s impacting the performance of the bike. There seems to be more friction than there should be in the bottom bracket area. If I take the chain off and turn the cranks, the effort required to do so is higher than on any of my Shimano-equipped bikes. There’s no grinding, crunching, or other not smooth feeling, but there is a steady rubbing sound while the cranks are turning. The feeling is similar to that of too much preload on the bearings, but Ekar bearing preload isn’t adjustable, so I’m not sure what step to take next. Any suggestions?
Just a few general comments, which may or may not be useful….
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How long have you had the BB installed? Some sealed BB’s take awhile to “break in”.
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The “spin” test, while somewhat natural to use, is not really a good indication of BB efficiency. BB’s are used under load and the spin test is basically without load, so not really indicative of actual performance.
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An incorrectly-faced BB shell can sometimes lead to binding in a BB, so you may want to have that checked.
Break-in is definitely something I’d considered, but it’s probably got nearly 2000 km on it at this point, so that seems unlikely.
Your spin test comment is noted, but I do feel that power transfer under load is less efficient than it should be. Then again, compared to a road bike, this bike is a pig anyway, so it’s hard to make a direct comparison. It feels slower to accelerate and harder to keep at speed than it should, though, even with that in mind.
Facing is another possibility; the bike was originally a (very lightly used) demo bike, and I have no idea how it was originally set up. I’ve made some changes to it since getting it, but not to that level of detail.
Just another data point - not sure if it’s useful, but I have seen a few bikes (more than what should be normal) with improperly installed BBs, i.e. cross threaded BB cups, probably installed by an unsupervised trainee, etc, which isn’t difficult, since the threads are pretty fine, especially if the mechanic is somewhat ham-fisted.
Cross-threaded BBs, together with incorrect facing, can also lead to increased friction.
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I had the same issue, and the BB shell was perfectly faced. The seals are very tight, and cause plenty of friction. What helped a lot, was installing new bearings where the grease was replaced with Black Diamond chain lube, and also the bearing rubber seals were stretched overnight over a socket that has slightly larger diameter than crank axle. The seals were also lubed with BD. They have been good now for over 10000 km’s.
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It’s quite easy to crush the wavy washer in the left cup if it moves slightly while installing the crank - it seems to move around more easily than the older ultra-torque ones. I would check that, and replace if needed. The seals are a little heavier on pro-tech, but it should still spin comparably to something like Shimano Hollowtech.
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