The Doctor Is Out, Moving From Harlem to Brooklyn. J. David Goodman in the Times' City Room Blog. Three paragraphs I hope will send you there. It's a wonderfully textured blog post, and a good story:

Mr. (Donald) Childs opened the shop when he was released from prison two years ago, he said, and for the first six months, the location was great for business. His name -- the bike doctor -- came from his use of a stethoscope to listen for loose ball bearings. "A lot of places will charge you to take it apart just to see what's wrong," he said. "I can tell without going in."

... Mr. Miller said he would continue to report the shop's violations of zoning and other infractions. "What's going on there is a cancer on the block," he said, objecting to the grease, the children who run into the street, and the mechanics and customers who hang out all day with Mr. Childs.

...Mr. Childs said he sees the move out to Brooklyn as a business opportunity. On a recent night, he visited a potential storefront on DeKalb Avenue and Clermont and was immediately taken by the borough's bike culture. "You look and it's like a hundred bikes on the block. They've got women on bikes with their dresses, with flowers -- it was like something out of the 18th century."