The good news is that this year you can still pedal your bike along First or Second avenues in Midtown when the United Nations General Assembly comes to the Big Apple this week.

The bad news is everything else.

Bus routes will be disrupted, roads will be closed — sometimes without notice — and Midtown will generally be a massive gridlock nightmare for drivers when the 74th gathering of world leaders convenes at First Avenue and 42nd Street.

The city is strongly urging travelers to rely on mass transit — or two wheels.

“The UN General Assembly sees some of Manhattan’s most congested days of the entire year,” Transportation Commissioner Polly Trottenberg said in a statement. “Drivers should leave their cars at home (this week) if they can — and try walking, taking mass transit, or getting on a bicycle.”

Average speed for cars drops to 4 mph during general assembly week — or 20 minutes to drive a mile, city transportation officials said.

According to transit and transportation officials, this is what you can expect through Sept. 30:

Vehicle traffic:

The best suggestion is to avoid driving in Midtown at all.

Numerous roadways will be closed for the UN gathering, including First Avenue between 42nd and 48th streets, and 44th Street to 46th Street between First and Second avenues.

Officials said 49th Street between Third and Lexington avenues will also be closed.

The FDR drive and other roads could be shut without notice for emergency vehicles or dignitaries.

Bus service:

Expect delays on all buses operating in Manhattan, with potentially “significant” delays or detours expected on the M1, M2, M3, M4, M9, M15, M20, M27, M42, M50, M66, M72, M101, M102, M103, M104, X25 and X90 bus routes.

Bike lanes:

The city will create temporary bike lanes for the first time during the general assembly.

Cyclists northbound on First Avenue will pass a security checkpoint at 39th Street, and will be able to pedal up to East 49th Street on a temporary bike lane. The lane will remain open around the clock.

A temporary bike lane will run southbound on Second Avenue between East 57th Street and East 41st Street. The existing bike lane will be kept clear for dignitaries and emergency vehicles. The Second Avenue lane will close down at 9 p.m.

Cyclists will be subject to security checkpoints and “unannounced traffic freezes” in both bike lanes.