I have 2 pc eclat aeons in 170mm and they rattle a lot when dropping the back end. Nothings wrong with the chain or bb, as they have both been replaced, and the chain is tight enough that it doesn't make any noise. My friend however has some blank cranks that are 3 pc, and make no noise when dropping the back end. I'm wondering if there's any way to dial my cranks so they make no noise, or if the reason is just because 3 pc are better made