The Bike Yield ordinance was heard by the full San Francisco Board of Supervisors yesterday. It passed, with six “ayes” and five against — two “ayes” short of what’s needed to override Mayor Edwin Lee’s veto pen.

The San Francisco Examiner reports that mayoral spokesperson Christine Falvey was ready with a response. “The mayor believes this endangers pedestrians and other cyclists and he said he will veto it in the interest of public safety,” Falvey said right after the vote.

The legislation would instruct the police to make ticketing cyclists who cautiously roll through a stop sign, while still yielding to others, a low priority. Yet District 2 Supervisor Mark Farrell said he was voting against it because he doesn’t want an “Idaho Stop,” referring to that state’s traffic laws, which allow cyclists to treat stop signs as yields. He noted that San Francisco is denser than Idaho.

Idaho isn’t the only place that gives cyclists more discretion at traffic control devices, however. Paris also permits cyclists to do rolling stops in some locations. In fact, Paris even allows cyclists to treat some red lights as yields. Paris is roughly three times denser than San Francisco.

Supervisor Scott Weiner, a sponsor of the bill, tried to get the arguments back on point, reminding others that the ordinance can’t change state traffic laws, and was written to dissuade cops from cracking down on cautious cyclists. “I don’t think that’s how we should be using our law enforcement resources while people are getting hit and dying on our streets,” he said.

“When there’s an anti-bicycle bias within the police — and it’s not just one or two cops—it’s counter to Vision Zero,” said Supervisor Eric Mar, who was also trying to focus the debate back on the purpose of the ordinance. “Unsafe bicycling is an issue but compared to the culture of speeding in cars, it’s like night and day.”

The supes will vote again on January 12. Then the mayor has until January 22 to veto. The Board of Supervisors can override, but as a legislative deputy at City Hall explained about Tuesday’s vote: “Whatever happens today will signal the fate of the Bike Yield law. If Farrell or Peskin join those in opposition, then it won’t have the votes to survive a veto.”

So it doesn’t look like this legislative remedy for poor SFPD enforcement priorities is going to pan out. But the question of how to tailor traffic laws to account for the differences between bikes has newfound prominence, and yesterday’s vote showed there’s significant political support for change. This won’t be the last time that adjusting the current rules comes up for debate.