I’ve found countersteering to be a very effective way of adjusting the angle of a motorbike while riding. You basically push the handlebars in the ‘wrong’ direction and the bike just leans over.

It’s scary when you first try it going down a motorway (it’s less sensitive at higher speed), but very effective indeed, and doesn’t require moving your centre of gravity.

I don’t pretend to be a professional racer though. They do seem to lean a lot.

PS. You can do this on a bicycle too, but the reduced momentum makes it much more sensitive.