Today's Observer draws attention to the Ghostbike phenomenon and its spread around the world.
First sightings were in St Louis (some say San Francisco) in 2003 but since then 68 cities in 28 countries have seen these simple - white-painted bike - shrines to make fatal bike accidents
Like cellotaphs but the cycling community's own version, created and spread by them alone. Here's Geoff Dyer on ghostbikes as art
And how do you think they spread?
Oh, yes: Copying