Originally Posted by smashndash

For BB30, you can do either. Reducers in direct bearings, or a sleeve with appropriately sized bearings. I prefer hambini because he uses standard 25mm bore bearings and a 1mm reducer, which opens up your bearing options a lot. You can get really nice or really economical bearings rather than Shimano specific ones. He claims his BBs are significantly stiffer, which may help with feel, but is mostly for bearing alignment. I’m indifferent to that since I’m quite light. But overall I’d recommend the Hambini one. Those NTN contactless seal bearings spin real fast.

of note: I’m currently using a BB30 to Shimano hambini racing BB. I can definitely feel some extra “eagerness” when out of the saddle, compared to my praxis thread together, which has questionable bearings.