What is Bicycle Day (and Why Is It Important to the World of Psychedelics)?

Not to be confused with World Bicycle Day—created by the United Nations to celebrate actual bicycles—April 19th is Bicycle Day, the day we celebrate LSD! But how did it get started?

On April 19, 1943, Swiss chemist Albert Hofmann took LSD. This became a famous exploration of LSD known as Bicycle Day. It was the start of a lifetime of advocacy for the Swiss scientist, but there is a lot more to the story.

bicycle day

Hoffman worked for Sandoz Laboratories of Basel, Switzerland studying plants and fungi such as ergot and their constituents for use as medications. On November 16, 1938, Hofmann first synthesized LSD while researching lysergic acid diethylamide derivatives to obtain an analeptic (a respiratory and circulatory stimulant).

Since the initial goal was a failure, Hofmann set aside LSD for five years, until April 16, 1943. That day, Hofmann accidentally absorbed a small amount (about 250 micrograms) of LSD while re-synthesizing it, discovering its powerful effects for the first time:

“[I was feeling] restlessness, combined with a slight dizziness. . .[and] a not unpleasant intoxicated-like condition, characterized by an extremely stimulated imagination. In a dreamlike state. . .”

Hofmann, escorted by his laboratory assistant, made his way home by bicycle, as was customary in Basel at the time due to wartime restrictions. The ride home was, shall we say, a bad trip for Hofmann—yet when they called the doctor, he seemed fine. He stopped feeling as scared and enjoyed the rest of his trip, later describing it:

Kaleidoscopic, fantastic images surged in on me, alternating, variegated, opening and then closing themselves in circles and spirals, exploding in colored fountains, rearranging and hybridizing themselves in constant flux.

Albert Hofmann

Those events, chronicled after the bike ride home, became known as Bicycle Day. (And while Bicycle Day is the most famous first acid trip most people know of, the phrase trip was coined in the 1950s by US Army scientists experimenting with LSD.)

That ride home was significant to Hofmann because it proved the existence of a highly potent, psychoactive substance that could cause major changes in consciousness at very low doses. In other words, because of the intense, introspective experience it produced, Hofmann could not imagine anyone using LSD recreationally, and saw it as a potentially powerful psychiatric tool.

Hofmann also studied magic mushrooms, and isolated the psychedelic compounds psilocybin and psilocin. Yet he always had complex feelings about the field of psychedelic chemistry—which he helped create. He even referred to LSD as “my problem child.” Hofmann felt that the experience itself was the medicine and that LSD was just a tool for human psychic evolution, improving mental health, and achieving well-being.

However, for people today in psychedelic communities, Bicycle Day is observed to celebrate the discovery of LSD and for a whole range of reasons, including its recreational use. The day itself was founded in 1985 by Thomas B. Roberts, a professor of psychology.

Modern versions of Bicycle Day celebrations might range from educational seminars on the effects of LSD to streaming social media events and online mental health exploration forums for psychonauts and some cannabis enthusiasts. There are even Bicycle Day playlists on Spotify.

Drop and discuss Jack Cowan’s hallucination hypothesis while your mind is generating the checkerboards, lattices, spirals, tunnels, and convective swirls all psychedelic users know and love. Or just gaze on familiar sights with a new eye as everything takes on a new, psychedelic, feathery, touchable glow.

The range of Bicycle Day events and initiatives gives a sense of the way interest in psychedelics and the previously forbidden transgression of limits they represent are exploding in popularity right now. You don’t have to be a cyclist to appreciate the possibilities of Bicycle Day.