Four days ago a guy riding in the Door Zone Bike Lane on Summit Avenue in St Paul got doored. He's been in intensive care since with a prognosis of likely brain damage. Last summer someone riding along this same DZBL swerved to avoid a door opening in front of them. The car coming up in the lane behind didn't have time to swerve. I believe she's in a wheel chair.

Many car doors can open to over four feet so I give at least five feet.