Several members have commented on the connection between arms makers and bicycles and yet another has popped up with Nick's post of a Gnome et Rhône bike. Gnome et Rhône produced rotary (not Wankel) aircraft engines that were used by both sides during the early part of World War I. The most well know model would be the LeRhône. German versions were licensed built under the label Oberursel. The company continued engine production between the wars and during the second world war produced BMW engines under license for the Germans. Post war, the company was nationalized to save it and became SNEMCA. Appears they also dabbled in motorcycles.
Link below has photos of a Gnome et Rhône bicycle