So, after much debating I decided to start my bike squad. Ultimately it will consist of sgt, 2 bikes and an attack bike, and will escort my version of the Master of the Ravenwing, but I only have the sgt and 2 bikes thus far. I have put them together, with the sgt being very highly decorated and the others less so. That sgt is going to be Conquest, his armor is gold, his bike white and trim done in reds, silvers and gold. One other bike, currently deployed with a bare head and bionic eye, will be Death, and he will have a sickly pale green bike, dead black armor and the skin that is visible will be very pale - I intentionally avoided giving him a hood because I think I may eventually build a marine named Thanatos. The last bike is going to be Famine, on a dead black bike - I haven't decided on his armor color yet, but I may actually make it bleached bone. War I'm saving for the attack bike, and it will be a red bike with the riders in red and black armor.
I chose Conquest over the later Pestilence interpretation because I didn't want to go over towards Nurgle too much, and figured it fit the idea of my army better. My idea actually came from my love of Albrecht Durer, so the change came later, largely after a conversation with Emily.
My Master of the Ravenwing will be done with large wings and be set up as the Angel who announced or accompanied the Horsemen to the Apocalypse. His wings and bike will be white and silver I think, and his armor black, red and gold.