Is it time to start calling out bad cyclists?

A Barclay's biker cut across me yesterday morning on the westbound junction of the Imax Roundabout, forcing me to stop before he moved onto the roundabout going the wrong way round it to then head north on the southbound side of Waterloo Bridge.

I called him a dickhead but he just ignored me.

hang on - was he on the road?! that is proper crazy behaviour if so.