I've been attempting to clean the frame up and drawing a blank at getting the black marks pictured below off. I've tried muc off bike cleaner and isopropyl with no luck. I can feel the marks when I run a nail over them so might need something with a bit more friction than a cloth to get them off. A couple of people have suggested tar remover or a clay bar, but any suggestions would be much appreciated!
I've been attempting to clean the frame up and drawing a blank at getting the black marks pictured below off. I've tried muc off bike cleaner and isopropyl with no luck. I can feel the marks when I run a nail over them so might need something with a bit more friction than a cloth to get them off. A couple of people have suggested tar remover or a clay bar, but any suggestions would be much appreciated!