I am occupying myself in the cold weather by building up another bike I don’t really need, but.. Anyhow, I will probably use a nice cromoly Shimano spindle and bb. That got me to wondering about the difference between those pretty silver cromoly spindles and the black ones. I did a minor search but didn’t see much.

I would guess harder steel? More durability? It may just be cosmetic, but it seems the cranks spin better too on the prettier ones. Is it also a combination of better cups too? Cheap spindles are available for maybe $10, so the premium older used ones must have something more going for them.