I'm going to California for a few weeks, largely the San Francisco and Los Angeles areas, and to save money (and time considering LA traffic) I plan to bring a bicycle with me and use that and public transport to get around.

Seeing as a lot of the rides are long and hilly, and I have a good deal of electronics experience, I'm strongly considering mounting a motor to the bicycle to make my commute a bit easier. Would a bicycle with a motor manually attached be street legal in California, specifically in Los Angeles and San Francisco?

  • What is the wattage of the motor? Does it stop assisting above a specific forward velocity? Does the bike still have functional pedals that propel the bike ? You may be better simply using the bike's gears and ride a bit slower up the hills.
    – Criggie
    Aug 17, 2022 at 19:37

1 Answer 1


There are state laws pertaining to the operation of motorized bicycles (Vehicle code 21207.5.

no motorized bicycle may be operated on a bicycle path or trail, bikeway, bicycle lane established pursuant to Section 21207, equestrian trail, or hiking or recreational trail, unless it is within or adjacent to a roadway or unless the local authority or the governing body of a public agency having jurisdiction over such path or trail permits, by ordinance, such operation

However, section 405 of the vehicle code distinguishes motorized bicycles and motor-driven cycles. Per 405:

A "motor-driven cycle" is any motorcycle with a motor that displaces less than 150 cubic centimeters. A motor-driven cycle does not include a motorized bicycle, as defined in Section 406.

It does not matter if you do it yourself.


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