A Small Cannabis Cycling Study Could Not Establish a Universal Inability-to-Ride Threshold
A small experiment in regular cannabis consumers did not establish a THC concentration that universally marks inability to ride a bicycle. Its limited findings should remain tied to the participants, cycling task and exposure procedure that were actually studied.
Who rode and under what conditions
Hartung and colleagues examined 14 regular cannabis consumers, including 12 men and two women. Participants underwent practical cycling assessments before and after inhalation, with a protocol allowing up to three weight-adjusted cannabis joints.
This was a human performance study of cycling in a selected group. It was not a representative survey of all cyclists, an experiment in cannabis-naive riders or a study of motor-vehicle crash risk.
Few faults did not define a universal threshold
The report described relatively few cycling faults even at high measured THC concentrations and could not define a concentration-based inability-to-ride threshold. That is a limitation on the proposed threshold, rather than proof that cannabis never affects cycling.
A small sample can miss uncommon errors and cannot capture every road demand. Performance on the tested task also does not establish performance during unexpected traffic events or operation of a different vehicle.
What the result can support
The study cautions against assigning a universal functional meaning to one THC number using this evidence alone. A conclusion about an individual rider still requires the actual observations and the circumstances of the event.
Its regular-user sample is particularly relevant to generalization. The findings should not be transferred automatically to infrequent users, other preparations or higher-risk environments. Neither a pass nor a concentration in this experiment supplies a general safety guarantee.
Related: Separating cannabis exposure, impairment and crash risk.
Research cited
Hartung B; Schwender H; Roth EH; et al.; International Journal of Legal Medicine; 2016. The effect of cannabis on regular cannabis consumers’ ability to ride a bicycle.
