Cal. Vehicle Code § 21211

(a) No person may stop, stand, sit, or loiter upon any class I bikeway, as defined in subdivision (a) of Section 890.4 of the Streets and Highways Code, or any other public or private bicycle path or trail, if the stopping, standing, sitting, or loitering impedes or blocks the normal and reasonable movement of any bicyclist. (b) No person may place or park any bicycle, vehicle, or any other object upon any bikeway or bicycle path or trail, as specified in subdivision (a), which impedes or blocks the normal and reasonable movement of any bicyclist unless the placement or parking is necessary for safe operation or is otherwise in compliance with the law. (c) This section does not apply to drivers or owners of utility or public utility vehicles, as provided in Section 22512. (d) This section does not apply to owners or drivers of vehicles who make brief stops while engaged in the delivery of newspapers to customers along the person’s route. (e) This section does not apply to the driver or owner of a rubbish or garbage truck while actually engaged in the collection of rubbish or garbage within a business or residence district if the front turn signal lamps at each side of the vehicle are being flashed simultaneously and the rear turn signal lamps at each side of the vehicle are being flashed simultaneously. (f) This section does not apply to the driver or owner of a tow vehicle while actually engaged in the towing of a vehicle if the front turn signal lamps at each side of the vehicle are being flashed simultaneously and the rear turn signal lamps at each side of the vehicle are being flashed simultaneously.