Study Concludes Biking While High on Marijuana Isn’t Dangerous


Bike messengers everywhere, rejoice: A new study has found that marijuana use appears not to negatively impact the ability to safely ride a bicycle.

The participants in the experiment rode a bike through an obstacle course while completely sober and then after smoking one, two and three joints.

“Hardly any coordinative disturbances could be detected under the influence of high or very high THC concentrations,” the study, published by the International Journal of Legal Medicine this week, found.

A representation of the course that participants had to bike while stoned.

A diagram of the course that stoned participants had to bike.

The study, titled, “The effect of cannabis on regular cannabis consumers’ ability to ride a bicycle,” was conducted by German and Austrian researchers.

The cannabis cigarettes, which were standardized to contain 300 micrograms of THC per kilogram of body weight, were supplied by Dutch grower Bedrocan with the approval of the German government. Test participants “were instructed to consume the joints in the following way: 4-s inhalation, 10-s holding breath, and 15-s exhalation,” the study says.

While cycling the obstacle course, the fourteen participants in the study were given demerits for errors like leaving the track, knocking over barrels, swerving, running a red light and failing to go at a green light. Along the way, they had to slalom between poles and were presented with distractions like balls rolling in their path, verbal interruptions and being subjected to the glare of torch lights.

“Hardly any driving faults occurred under the influence of cannabis,” the researchers wrote. “Only a few driving faults were observed even under the influence of very high THC concentrations… On average, there is no increase in the number of demerits after the cannabis consumption.”

None of this is to say that operating any vehicle, particularly automobiles, while under the influence of marijuana or other drugs, is recommended.

Driving while stoned is illegal, even in states that have ended cannabis prohibition.

About Author

Tom Angell covers policy and politics for Separately, he serves as chairman of the nonprofit organization Marijuana Majority, which works to ensure that elected officials and the media treat legalization as a serious, mainstream issue. Marijuana Majority led the effort to get the U.S. Conference of Mayors to pass a resolution telling the federal government to respect state marijuana laws, and orchestrated the first-ever endorsement for marijuana legalization by a U.S. Supreme Court justice (John Paul Stevens). Previously, Tom worked for Law Enforcement Against Prohibition and Students for Sensible Drug Policy. (All organizations are listed for identification purposes only.)


  1. The study was obviously flawed. 4s inhalation, 10s hold, and 15s exhalation is just plain wrong. Where’s the 30 seconds of coughing after hot boxing that joint?

        • In Science We Trust on

          I have excellent lung control and that’s why it doesn’t take me 15 seconds to exhale. In fact my brain probably functions at a higher level because I don’t take 15 seconds to exhale.

          • You said “please teach me how to…”, which is something people usually ask when they don’t know how to do something.

            “I have excellent lung control and that’s why it doesn’t take me 15 seconds to exhale.” — Actually, it takes more lung control to exhale in 15 seconds than it does to exhale in 5.

            “In fact my brain probably functions at a higher level because I don’t take 15 seconds to exhale.” — You think you’re funny, huh? Try again.

            That being said, it’s true that exhaling for 15 seconds vs any other amount of time does NOT affect the amount of THC that gets into your system. I don’t know why they had them exhale for 15 seconds vs. just 5 seconds, and I admit, I was a little confused when I saw that.

    • 95% of THC is absorbed by the lungs within three seconds. Holding in for longer makes no discernible difference. Any claims of holding in for longer producing a bigger high is either the placebo effect or oxygen deprivation.

  2. Bike messengers already knew this. Are they supposed to “rejoice” because “science” has finally come to ts senses?

  3. Although the US government would never allow scientific testing of Marijuana for beneficial use, back in the 1970’s a somewhat scientific test was performed on professional race car drivers to determine if THC hampered a professional drivers ability to operate a car. In almost all cases, the drivers performed superiorly on the track when under the influence of Marijuana.

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