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Quick google suggests Angular contact bearings are designed for applications which need to support both axial and radial forces like headsets which turn and also are subjected to force up the steerer when hitting bumps etc. Cranks will naturally have some radial force side to side but I would think its minimal in relation to the axial forces.
But I don't have a fucking clue what I'm talking about
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In standard radial bearings, only 3 or 4 balls make contact during the load, at any given time. In Angular Contact bearings, ALL balls are engaged
Bullshit in the context of hubs and BBs where two radial bearings are preloaded against one another and act exactly like a pair of angular contact bearings. The only advantage of an ACB in that case is that you can stuff bigger bearings into the same hole, and BB30 bearings are already plenty big enough. If you want the biggest possible ACBs in your hubs, buy Shimano.
"Enduro Angular Contact bearings are specifically designed for hubs and bottom brackets. In standard radial bearings, only 3 or 4 balls make contact during the load, at any given time. In Angular Contact bearings, ALL balls are engaged and spread the force over a larger surface area, to decrease friction, and minimize wear."
It's not shit on paper. But the current BB is clicking so maybe it is.