It doesn’t cost much to make a stripped-down white bicycle to leave as a memorial near the spot where a rider died.

The bike is free. The spray paint costs maybe 98 cents a can, three or four of which will cover a bike. Pulling off the bike’s chain, its brakes, its pedals, flattening the tires or filling them with concrete so there is nothing of worth to steal — those take little energy. What is left is pristine and ethereal. Clean.

The lives the ghost bikes represent, however, are not cheap. Not to Nick Drombosky. In August 2009, the 23-year-old made the first such memorial, called a ghost bike, that the city had seen since 2004, and he locked it to a utility pole near the University of Pittsburgh at the tight, busy intersection of Meyran Avenue and Louisa Street.

It is a quiet reminder of Rui Hui Lin, a 38-year-old take-out delivery rider whom a driver hit there. Mr. Lin died after he was taken to the hospital. His death was the first in Pittsburgh of a bicyclist hit by a car since 2004. Mr. Drombosky also made the signs that accompany the bike and tell only a little of Mr. Lin’s story — father of two, bicyclist, dead.

“It’s such an odd thing to do,” Mr. Drombosky said. “I know that. For a stranger to care about someone or an event they had nothing to do with is odd in our society. But I feel like it shouldn’t be.”