I did a search for bike repair and got several. These work so maybe thats the way to map one. http://www.openstreetmap.org/way/344904107 https://www.openstreetmap.org/node/3465734855https://www.openstreetmap.org/node/3465734855 Sorry it seems you are not looking for businesses (shops) more of a self repair amenity see links below.

I did a search for bike repair and got several. These work so maybe thats the way to map one. http://www.openstreetmap.org/way/344904107 https://www.openstreetmap.org/node/3465734855