How to ride LEGAL in Colorado?


Local time
11:50 AM
Aug 19, 2011
Hello all!
First post here!
I'm trying to get a bike set up to ride, however i want to make sure it is/i am as legal as possible. I was planning on getting a setup from craigslist for a 66cc kit with a jack shaft.

Colorados laws state that the bike has to be registered with a tag on the bike.
After multiple trips to the Motor Vehicle department and even the police station... i'm stumped as to what i need to do!

Motor Vehicles sent me to police and said they couldnt give me the registration sticker. after an hour consulting with an officer, i was directed to a different officer. Here's the info i was given:
1) the bike has to have a VIN number to be issued the registration sticker.
2) in order to get a VIN number, the bike needs to go through a VIN inspection from the Colorado State Patrol.

Now here's the issue. The kit i am buying is a 66cc, but colorado law states that the engine has to be under 50cc. The officers i talked to said that it may not matter much of the engine size depending on how thorough the inspection is. Has anyone gone through this process?! seems like for such a popular mode of transportation, the police are really not on top of it!
#1. IF you must ride "legally", get a 48 c.c. engine and not a 66 c.c
they run the same, look the same, the 49's don't have the vibrations that the 66's have, and actually a 49 c.c. will outrun a 66 c.c. when set up and tuned right.

#2. LIE. tell them that your 66 c.c. is a 49. c.c. the only way they would be able to tell that it's a 66 is if they pull the engine apart and measure the bore, and stroke.

#3. if you can't get the vin #, just ride it and don't get caught. IF you do get caught, play dumb...say you had no idea that there was a law against them and again, say it's 49 c.c.'s.

I'm sorry if you don't feel the same way that i do, but this is the way i'd do it.
I have been riding for 3 years now, and the only time i have been "stopped" by the cops was so they could check out my bikes and tell me how cool they are.
Motorpsycho point #1 is your best advice if you want to ride legally with least frustration, as you are discovering. I will add: if you want it legal with a larger engine, you will need to make it motorcycle-fitted: no more than two headlights, working horn, taillights (a "should-have" anyway), turn signals are optional, and more. A state-issued VIN is a painful paperwork process. I have not found an insurer who will insure a vehicle that does not have a VIN.

I have over 1500 miles on Colorado roads. I have been seen and passed on the road by many city, county and state law officers. None have looked at me even twice probably because 1) I wear a white motorcycle helmet, 2) wear a bright yellow nylon jacket, 3) stay under posted speed, and 4) obey all other laws of the road. I ride a 66cc build.

Your engine will probably have nothing on it to state what size it is. If you don't give law officers reason to stop you, they will leave you alone.
Super! from what i hear it sounds pretty easy to just say "heres my setup, its a 49cc" with no problem. Now my only other question would be, how many hours are these little engines good for before they need a rebuild?
Will - You have a LOT of reading to do. The answer will range from zero to thousands of miles. (That zero was mine, by the way. I almost trashed a brand new engine after tightening head studs to "recommended torque". Studs stripped out the case threads. I tore it apart into pieces, got replacement parts, and later placed over 1300 miles on that engine.) Someone else will claim the high-mileage record. . . .

Research the continuing debate about engine oils. Engine life is often a function of how hard or easy you ride the engine. Like a race engine, life seems to be inversely proportional to the way you ride. And that is a function of how the rider treats it.

Enjoy reading and researching!

Summary of laws regarding the use of under 50cc motorized vehicles in Broomfield:

� Motorized Bicycles MAY be ridden on public roadways.

� Motorized Bicycle riders must have a valid driver's license, but are not required to have a motorcycle endorsement.

� Motorized Bicycles ridden on public roadways must have a valid registration decal.

� Motorized Bicycles ridden on public roadways are not required to have insurance.

� Motorized Bicycle riders and passengers must wear eye protection. Colorado currently has no helmet law.

� Motorized Bicycle riders must obey all laws applicable to other motor vehicles.

� Motorized Bicycles MAY NOT be ridden on sidewalks, bike trails, parks, fields or any other areas commonly used by pedestrians and bicycles.

� Motorized Bicycle riders under the age of 18 must wear a helmet per C.R.S. 42-4-1502 (4.5)(a)(I).

Are riders of Motorized Bicycles, Motor-driven Cycles, Motorscooters and Motorbicycles required to have a driver's license?

YES. If the engine size is under 50 cc, the rider is required to have a valid driver's license, but not a motorcycle endorsement, to operate it on a public roadway. Colorado Revised Statute 42-2-103 not only requires motorized bicycle riders to possess a valid driver's license, but it also prohibits them from riding on interstate systems, except where bicycles are allowed.

Are these vehicles required to be registered?

YES. Colorado Revised Statute 42-3-311(1) requires these vehicles be registered through the Department of Revenue, Division of Motor Vehicles Registration Section. Upon registering the vehicle, a number decal shall be securely affixed to the motorized bicycle frame in a conspicuous place. The registration is valid for 3 years. Further information and necessary forms can be found at

Are these vehicles required to be insured?

NO. If the engine is under 50 cc, it is not considered a "motor vehicle". Colorado Revised Statute 42-4-1409 and Model Traffic Code 1409 require only "motor vehicles" carry a current insurance policy.

Are riders of these vehicles required to wear a helmet and eye protection?

In Colorado there is currently no law requiring riders or passengers to wear a helmet, although it is always recommended.
Colorado Revised Statute 42-4-232(1) and Model Traffic Code 232(1) require that both riders and passengers wear goggles or eyeglasses with lenses made of safety glass or plastic.

Are riders of Motorized Bicycles, Motor-driven Cycles, Motorscooters, and Motorbicycles required to abide by traffic laws?

YES. Colorado Revised Statute 42-4-109(1) and Model Traffic Code 109(1) state in part:

Every person riding a motorized bicycle upon a roadway where motorized bicycle travel is permitted shall be granted all of the rights and shall be subject to all of the duties and penalties applicable to the driver of a vehicle

does this clear things up for you???
Last edited:
from the link darwin posted...
Deletes the definition of motorscooter and motorbicycle 42-1-102(59)(a) and motorized bicycle 42-1-102(59)(b).

look up the statutes and what i posted was copy and paste from the link at begining of the post...
Hey, go easy on Ibedayank. He is correct in every line. I read the town of Broomfield's rules myself two years ago. They are the most easily read and easily understood of any rules put out by a Colorado town. The laws published by the STATE government are a lot more messy to understand and are more subject to more variations of interpretation.
OK we'll agree to disagree, the way I read it the low power scooter law does not apply to bicycles. This law was designed for the proliferation of under 50cc Scooters running around lately and you do need insurance for those. A bicycle is not a scooter and noone thats sane will call a bicycle a scooter............anyways have fun I am.