The 2017 bike map for all of Brooklyn looks like this. It’s pretty easy to see that bicyclists have a number of safe options in the northern half of Brooklyn, and very few in the southern half.
The unedited map of southwest Brooklyn — south of Greenwood Cemetery, west of Ocean Parkway — clearly shows a big goose-egg for neighborhoods like Dyker Heights and Bensonhurst, but implies that there are a few options for getting from Bay Ridge into and through Sunset Park.
Unfortunately, there are a few problems with this map.
Not bike lanes: the routes marked in purple are called “shared lanes” by the DOT (or Class 3 bike routes). They are marked by the silhouette of a bicycle with two chevrons or “sharrows” pointing forward. But there is no line separating the bike lane from the car/truck lane. Each has full legal right to the use of the full lane. There is another kind of street not marked on the map where this is also true. It is called “almost every other street in the city.”
Suicide by bike: the routes marked in that non-descript salmon or peach-fuzz color are called “signed routes” by the DOT. They’re like “almost every other street in the city,” with the important distinction that they seemed to be placed in areas with high traffic speed and volume to encourage maximum thrill for anyone that makes the mistake of riding a bicycle there. In this case, the DOT thinks biking on 4th Avenue through Sunset Park, the Belt Parkway service roads east of Bay Parkway, and the Cropsey Avenue Bridge to Coney Island are good places for you to die.
Incorrect on map: the map indicates that 7th Avenue through Sunset Park has a “conventional bike lane” (or Class 2 bike lane) in the parlance of the DOT, but this is a mistake. It was downgraded to a shared/Class 3 route a few years ago, and therefore (as noted above) is not actually a bike lane.
Unmarked: there are signs along 12th Avenue at the northern fringe of the region that indicate that bike lanes are for bicycles only and no other type of vehicle. Unfortunately, no one actually painted bike lanes on the street. See above for “not a bike lane.”
Removing all of the errors and the “Class 3” bike routes, and leaving behind only the ones that have segregation between bike and car traffic, the map looks like this:
By comparison, the northwest and northeast sections of Brooklyn provide much safer biking options (shown here at roughly, though not exactly, the same scale). Even southeast Brooklyn seems to have us beat — the Bedford Avenue bike lane at least provides one additional north-south corridor, and the DOT has an active plan in place to improve access from Sheepshead Bay and Canarsie to the Jamaica Bay area [PDF].