Originally Posted by
Andrew R Stewart
Because it's easier to access the bearings for adjusting purposes if they are the outer set. Andy
To add, it's likely impossible to adjust any non-outer bearing, so angular contact on an inner bearing is a no-no. Even if it were possible to adjust an inner bearing, the odds of getting any more than the outer pair properly adjusted are astronomical. Think about Newon's 3rd law. The preload on any single pair will always be equal, but if more than two are involved there's no assurance that all the bearings will be equally loaded.
In any case, you're greatly overthinking this. The question you need to ask yourself is what advantage do you hope to achieve with angular contact bearings. Without a material reason to try to out think the designers at White,there's no reason to assume that there's anything to gain.