Street Legal Requirements

Because the car will be a 3-wheeler, it will technically be classified as a motorcycle for safety purposes. This greatly reduces the amount of legally-required equipment, thereby following our main design principles of simplifying and adding lightness.

California CHP

Since I live in California and the car will technically be a “motorcycle,” I need to follow the California Highway Patrol (CHP) rules for motorcycles.

California DMV

Since I live in California and am building the car myself, I need to follow California Department of Motor Vehicles (DMV) rules for specially constructed vehicles (SPCNS).

Federal Motor Vehicle Safety Standard (FMVSS)

The US Department of Transportation (DOT) Federal Motor Vehicle Safety Standards and Regulations (FMVSS) govern what safety equipment must be install on all vehicles. The standards are here. The actual laws are here.

FMVSS 108 regulates vehicle lighting.


Motorcycles in California are required to have a horn.

Standard motorcycle horns are pretty wimpy and ineffective. I like the BansheeHorn that Peter Olt has designed.


Motorcycles in California are required to have one rear-view mirror. FMVSS 111 regulates mirrors. The absolute minimum size for motorcycle mirrors is convex mirror with “6450 mm2 of reflective surface.” Since a circle encloses the largest amount of area in the smallest amount of space, the smallest possible mirror would be a circle. The area of a circle is pi*r^2, so the smallest possible mirror would have a reflective surface with a radius of sqrt(6450/pi)=45.3 mm. So the smallest possible mirror would be a convex mirror with a diameter of 3.57 inches. For a flat mirror, the smallest possible diameter is 3.99 inches. What’s interesting is that a lot of companies sell 3″ diameter mirrors, which would be illegal in the US.

One of the smallest mirrors I’ve found in the stock Yamaha XT 500 mirror.



CHP and federal rules state that the headlamp must be mounted between 22 inches and 54 inches above the roadway. Whenever the motor is on the low beam must be lit.

The headlamp system consists of a high/low headlamp unit, a switch for off/on switch for the high beam, and a high beam indicator lamp for the dashboard.

I’m planning to use a single LED headlamp from Truck-Lite:


This LED unit pulls just 1.8 amps under low beam, as opposed to 4.6 amps for a standard 55 watt 7″ H4 motorcycle headlamp.

Stop Lamp / Tail Lamp with Reflector

For motorcycles, the CHP requires a single stop lamp, a single tail lamp and a single rear red reflector. To save weight, these three components can be combined into a single assembly.

The lamp “shall be mounted between 15 and 72 inches above the roadway.” Really? 72 inches? Now I’m no politician, but I don’t think we should be allowing 6-foot-tall motorcycles on the road. Federal regulations also require a minimum mounting height of 15 inches.

The CHP rules state that the tail lamp “shall be visible from 1,000 feet to the rear.” This leads to all kinds of questions. In what kind of environment? Pitch darkness? Full daylight? Visible through a dense fog or the perfect vacuum of outer space? And 1,000 feet where? Straight back? So I could use a laser and and could only see it 1,000 feet back if you were standing in exactly the right spot? This kind of ambiguity would never fly in a formula racing rule book, but apparently government lawmakers aren’t engineers, they’re politicians.

I’m planning to use a simple plastic LED tail light from KC HiLights:


Turn Signal Lamps

Turn signals are required in California for newly-built motorcycles. The front turn signals must be spaced at least 16 inches apart. The rear turn signals must be spaced at least 9 inches apart. They all must be mounted at least 15 inches above the roadway. They must be amber lamps and they must flash simultaneously.

A turn signal system consists of four turn signal lamps, an on-off-on switch, a turn signal flasher relay, and an indicator lamp on the dashboard.

License Plate Holder and License Plate Lamp

California motorcycle license plates are 7″ x 4″ with 1/4″ bolt holes on the four corners 5-3/4″ apart from each other horizontally and 2-3/4″ apart from each other vertically. According to Section 5201, California motorcycle plates must be mounted horizontally between 12 inches and 60 inches off the ground.


Three-wheeled motorcycles in California are required to have fenders on each wheel. The fenders must be at least as wide as the “tire thread” and must “effectively minimize the spray or splash of mud or water to the rear.” I’ve never heard of a tire “thread” before, only a tire TREAD and the CHP doesn’t define the word “thread.” This entire forum post is dedicated to figuring out what is meant by “tire thread.” I’m going to assume the worst case scenario and design the fenders to be the full width of the tire. In order to “effectively minimize the spray or splash of mud or water to the rear,” the minimum possible fender size would begin at the top of the tire and end 90 degrees later at the rear.

Passenger Seat and Footrests

Motorcycles that are capable of carrying a passenger must have a dedicated seat and footrests for the passenger.


California has a helmet exemption for “fully enclosed three-wheeled motor vehicle that is not less than seven feet in length and not less than four feet in width, and has an unladen weight of 900 pounds or more, if the vehicle meets or exceeds all applicable FMVSS and the requirements contained in the VC.” But since I am not fully-enclosing the vehicle, both driver and passenger will be required to wear helmets.

Minimum Seat Height

Keeping the seat height as low as possible allows the vehicle to have a lower center of mass, which improves handling, and creates a lower aerodynamic wetted area, improving top speed.

While California has laws banning “ape hanger” handlebars, there doesn’t seem to be a law about minimum seat height. I also can’t seem to find any federal law governing minimum motorcycle seat heights. New York has a minimum seat height of 20 inches for 3-wheeled motorcycles and 25 inches for 2-wheeled motorcycles. Connecticut’s minimum motorcycle seat height is 26 inches. Alberta has a 650mm (25.6 inch) minimum.

Looking at seat heights of 187 production motorcycles (excel sheet here), we see that most motorcycles have a 27 inch or 33 inch seat height:


Optional Equipment

There are rules for optional equipment like fog lamps, front reflectors, modulating headlampswindshields, speedometers, odometers, tachometers, , etc. Since these components are not required, I will not install them since doing so would violate my design principles of simplicity and lightness.

I plan to include a mobile phone mount on the steering wheel with a built-in charging cord. That way I can run the trapster app which will both tell me my current speed and alert me to police speed traps. In order to hear the speed trap alerts, you can buy a helmet with a built in bluetooth system.

Radar Detectors and Laser Jammers

Radar detectors are legal in California. I plan to design in a mounting system for a Valentine One radar detector with a direct-wire power adapter.

Laser jammers are illegal in California.

Will Martin is an energy analyst and expert on peak oil and alternative currencies. He is an MBA graduate of Cornell University, where he was a Roy H. Park Leadership Fellow and concentrated on studying sustainability in business through the school’s Center for Sustainable Global Enterprise. Prior to his MBA, Will worked in the energy industry, living in Singapore, Houston and Dubai. Will is a recipient of the 2012 “Pioneer Award” from the Association for the Study of Peak Oil and Gas (ASPO-USA). He currently works as a carbon trading commercial adviser in the San Francisco Bay Area. Will is a bitcoin enthusiast and in 2014 published the book “Anonymous Cryptocurrencies,” which became a #1 best seller in 3 Amazon categories and was the first book to be sold on a decentralized marketplace.

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