Milling, rain grooves what ever, there is also riding across a metal mesh bridge. All lots of fun. One area not mentioned is where the blacktop has been milled off, road usually a highway, not resurfaced and the old very worn and smooth cement is the surface.
My list of OH S^&T surfaces.
1. Metal mesh bridge, glad it was only 100 yards, Thrilling.
2. Newly milled black top, it happens a lot in the North East, most recent Rt 202 in MA went for 5 miles it was no fun. Just SLOW down and take it easy.
3. Blacktop has been milled off, very smoooooth concrete surface, feels very awkward, kind of sailing along, worst part is if you get in a lower milled area or grove and bounce around in the grove.
4. Blacktop patching is some crap that cracks in blacktop are filled with, some roads in CT are almost all this very smooth black stuff.
Please if you have more suggestions please update the list.