It's the last Friday of the month, and you know what that means: Critical Mass. The monthly “organized coincidence” of bike riders kicks off at 6 PM at Justin Herman Plaza.

"There will be heavy traffic in the area," The SFMTA warns, as they do every month. "Motorists are advised to allow extra travel time," they say—and the same goes for people taking surface Muni routes, as anyone who's been stuck on the bus as cyclists stream merrily by can attest.

Another possible complication to downtown traffic Friday night (though since Critical Mass routes aren't pre-announced, we're just guessing) is the SF Giants' pre-season game against the Oakland A's. The game begins at 7:15 at AT&T Park, which means SoMa could become a volatile mix of orange-clad pedestrians, drivers trying to get to the game (or the freeway), and folks on bikes.

We at SFist urge everyone to keep their patience and to and stay frosty. You'll all get there. we swear.