How to shine up old anodized aluminum?

[robot.hebobo]

If it's a clue to how these marks occurred, one thing to note is that this bike is from Minnesota, USA, where we have very cold winters, and a lot of salt is put on the roads. The original owner hadn't taken the best care of the bike, and I would not be surprised if it was ridden in the winter where it got salt on it...

 

[d8mok]

All that is common on Shimano parts. They are clear anodised or silver anodised.

You can’t polish anodising but you can polish it off (remove it completely ) by hand or by chemicals.

Scotch pad is an easy way to also remove it without the chance of leaving metal bits stuck on the alloy surface.

If you are wanting to restore them fully. Much easier and cheaper to buy a nicer set and sell those.

If you want them to look “ok” then just leave them as they are with the patina.