Got the new rollercoaster wheels and wanted to have a look at their potential.
They are smaller than the smallest train wheels that existed till now!
(Well, actually the wheels are the same outside diameter as the smallest wheels but the flange is much much smaller...)
I used a 1x2 plate with rail (with a normal 1x2 plate in between) to hold them. The thickness of the wheel axle is the same as that of Lego's tubes, which makes it hard to connect it while still letting it roll free. They can fall out of the base easily, but often enough also stay "fixed" when lifted.
As those two wheelbases are very short they also take curves with ease.