I definitely remember seeing 1:18th racing style bicycles somewhere before (perhaps on scale 18?). They were pretty basic without any fine detail, but that's all I can remember.... Sorry I'm not much help! :giggle :cheers
They are indeed 1:12. It comes under the Tour de Maisto category. Around here they cost some 5$. Pretty good detail and a nice addition if you are into cycling.
Edit: Sorry I do not know of any 1:18 bicycles.