I like the composition Mark. I can see the dark detail too. I wouldn’t mind seeing the colour version. Maybe with a touch of velvia to give it a little punch. :)
I see what you saw Mark but I wouldn’t be too pushed in maintaining detail in the shadow – I know, it’s a PI mantra but the focus for me is the wheel itself. The foreground chequer plate is quite bright which is also pulling you away from the focal point. Personally I’d be looking at isolating it a bit more.