ghost cycle
n.— «Bicycles painted stark white are chained to stop signs and telephone poles at nearly 40 locations around the city. An eerie visual reminder of the dangers cyclists face every day on local streets, these “ghost cycles” appeared at sites where someone reported a collision or dicey riding conditions.» —“‘Ghost bikes’ offer eerie reminder to share the road” by Kristin Dizon Seattle Post-Intelligencer (Washington) Aug. 3, 2005. (source: Double-Tongued Dictionary)