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Study: Smoking joints doesn't affect regular cannabis users' cycling ability

No difference found in negotiating obstacle course when clean or after three joints, say researchers

A new study says that smoking a joint - or three - of cannabis does not affect the ability of regular users of the drug to ride a bicycle.

Led by Dr Benno Hartung of the University Clinic in Düsseldorf, researchers had the 14 participants in the study – 12 men and two women – ride around an obstacle course.

Each undertook a number of rides on the course, the first sober, the others after smoking one, two or three joints, reports the Smell the Truth blog on the San Francisco Chronicle's SF Gate website.

For each puff of the joint, they were required to inhale for four seconds then hold their breath for a further 10 seconds.

They had points deducted for riding errors such as ignoring red traffic signals, hitting obstacles and going off course, enabling researchers to draw up a score for each run.

 The study, published in the International Journal of Legal Medicine, concluded: “Hardly any coordinative disturbances could be detected under the influence of high or very high THC concentrations.

“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.”

However, the study’s authors underlined that participants were regular cannabis users and that the research suggested habitual users have a different response to THC than those who do not use the drug.

 “A defined THC concentration that leads to an inability to ride a bicycle cannot be presented,” they said.

“The test subjects showed only slight distinctive features that can be documented using a medical test routinely run for persons under suspicion of driving under the influence of alcohol or drugs.”

Last May we reported on two other studies led by Dr Hartung that assessed the ability of people to ride a bike while under impaired – one when drunk, the other while hungover.

> Study: Men safer in the saddle than women when extremely drunk

> Riding the morning after: How safe is hungover cycling?


Simon has been news editor at since 2009, reporting on 10 editions and counting of pro cycling’s biggest races such as the Tour de France, stories on issues including infrastructure and campaigning, and interviewing some of the biggest names in cycling. A law and languages graduate, published translator and former retail analyst, his background has proved invaluable in reporting on issues as diverse as cycling-related court cases, anti-doping investigations, and the bike industry. He splits his time between London and Cambridge, and loves taking his miniature schnauzer Elodie on adventures in the basket of her Elephant Bike.

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