I watched Yannex play "4807m" by DooMeeR, an ice RPG map. One of the early CPs (3 or 4) consists of riding a vertical icy wall. The dynamic being used is the fact that counter-steering, when holding the gear, allows to turn quite sharpy on ice, with grip that does not seem to depend on gravity. It is therefore possible to stick to icy walls!
This map is one of my first ones, and definitely the first difficult/ice map I'm creating. It ends with my take on an ice wall, and has a few stunts before. I got a bit carried out regarding the scenery.
The author time is quite bad. As someone mentioned on the review server, I cannot even drive my own map! Yes, it is a hard map.