Mother's Billet from any auto store! Just follow the instructions, and do use a very soft cloth for the end step. A dollar store near my house sells the really nice fine cloths for $1, so I don't feel bad getting it all black.
You'll be very impressed! And the product also protects. My aluminum cranks now have a mirror finish that's lated three months!
I cleaned a 15 year old Alu Rocky Mountain that went from mat grey to super shiny. I could see my reflection in the welds.
There's only one danger, you'll want to polish all your components, and friends' bikes, and...