Bicycle Day
April 19
About Bicycle Day
Bicycle Day is observed on 19 April each year, marking the date in 1943 when Swiss chemist Albert Hofmann undertook the first intentional LSD trip and his now-legendary bicycle ride home through the streets of Basel, Switzerland. The day is recognised internationally as a milestone in the history of psychedelic science and pharmacology.
What is Bicycle Day?
Bicycle Day commemorates Albert Hofmann’s self-experiment on 19 April 1943, when he deliberately ingested 250 micrograms of lysergic acid diethylamide (LSD-25) to test its psychoactive properties. The name refers to the bicycle ride Hofmann took from his laboratory at Sandoz Pharmaceuticals to his home in Basel, during which the effects of the substance began to take hold. The day is observed by researchers, historians, and advocates of psychedelic science as a significant moment in the understanding of consciousness and neuropharmacology. It is distinct from World Bicycle Day on 3 June, which celebrates cycling as a mode of transport.
When is Bicycle Day?
Bicycle Day falls on Sunday, 19 April 2026. It is observed every year on 19 April, the anniversary of Hofmann’s 1943 self-experiment. The date is fixed and does not change from year to year.
The Story Behind Bicycle Day
Albert Hofmann first synthesised LSD on 16 November 1938 at Sandoz Laboratories in Basel, Switzerland, while researching ergot alkaloid derivatives in the hope of developing a respiratory and circulatory stimulant. The compound was shelved after initial tests showed no remarkable pharmacological properties. Five years later, on 16 April 1943, Hofmann returned to LSD-25 on a hunch that its effects deserved further investigation. During the re-synthesis, he accidentally absorbed a small quantity through his fingertips and experienced unusual sensations, including restlessness and mild visual distortions.
Intrigued by the accidental exposure, Hofmann decided to conduct a deliberate self-experiment three days later, on 19 April 1943. He ingested what he believed to be a cautious dose of 250 micrograms — later understood to be several times a threshold dose. Within an hour, the effects became overwhelming. Wartime restrictions meant private car use was prohibited in Basel, so Hofmann and his laboratory assistant set off on bicycles for the journey home. The ride became a harrowing experience as the full psychoactive effects took hold: Hofmann reported distorted perceptions, anxiety, and the sensation that he was barely moving despite pedalling steadily.
Upon arriving home, Hofmann’s condition fluctuated between terror and wonder. He feared he had poisoned himself fatally, and his neighbour who brought milk appeared to him as a malevolent witch. Gradually, however, the frightening visions gave way to calmer, more beautiful imagery. By the next morning, Hofmann felt refreshed and reported a heightened sensitivity to colour and form. He documented the experience meticulously, and his report became one of the most cited accounts in the history of psychopharmacology.
The term “Bicycle Day” was coined in 1985 by Thomas B. Roberts, a professor of educational psychology at Northern Illinois University, who organised the first celebration of the anniversary. The observance has since grown into an internationally recognised date, marked by lectures, art exhibitions, and discussions about the past and future of psychedelic research.
Why Bicycle Day Matters
Hofmann’s discovery opened an entirely new chapter in neuroscience and psychiatry. LSD became one of the most studied psychoactive substances in the mid-twentieth century, with thousands of research papers published between the 1950s and 1960s. After decades of prohibition, psychedelic research has experienced a significant revival in the twenty-first century, with institutions such as Johns Hopkins University and Imperial College London conducting clinical trials on psilocybin and LSD for treatment-resistant depression, PTSD, and end-of-life anxiety. Bicycle Day serves as a reminder of the scientific origins of this field and the ongoing conversation about the therapeutic potential of psychedelics.
Noteworthy Facts About Bicycle Day
- Albert Hofmann ingested 250 micrograms of LSD on 19 April 1943 — several times what is now considered a threshold dose of around 20-30 micrograms.
- Hofmann lived to the age of 102, passing away on 29 April 2008 in Basel, Switzerland.
- The term “Bicycle Day” was coined by Professor Thomas B. Roberts at Northern Illinois University in 1985.
- Between the 1950s and 1960s, over 1,000 clinical papers were published on the therapeutic applications of LSD.
- Hofmann himself called LSD “medicine for the soul” but strongly opposed its recreational use.
How to Observe Bicycle Day
Bicycle Day is primarily an occasion for education and reflection rather than conventional celebration:
- Read Hofmann’s account — His book LSD: My Problem Child provides a first-hand account of the discovery and its aftermath.
- Attend a lecture or seminar — Many universities and research institutions host events discussing the state of psychedelic science around this date.
- Visit an exhibition — Art galleries and cultural centres sometimes feature psychedelic art or the history of consciousness research.
- Watch a documentary — Films such as The Sunshine Makers and Fantastic Fungi explore the broader context of psychedelic research.
- Support research organisations — Groups such as the Multidisciplinary Association for Psychedelic Studies (MAPS) fund clinical trials and advocacy work.
- Go for a bicycle ride — In a nod to Hofmann’s famous journey, many mark the day with a leisurely bike ride.
Frequently Asked Questions
What is Bicycle Day?
Bicycle Day marks the anniversary of Swiss chemist Albert Hofmann’s first deliberate LSD trip on 19 April 1943, including his famous bicycle ride home from the laboratory in Basel, Switzerland.
When is Bicycle Day in 2026?
Bicycle Day falls on Sunday, 19 April 2026.
Is Bicycle Day about cycling?
No. Despite the name, Bicycle Day commemorates a landmark event in the history of psychedelic science. The bicycle ride was incidental — Hofmann cycled home because wartime restrictions prohibited car use. For a cycling-focused observance, see World Bicycle Day on 3 June.
Spread the Word
Help raise awareness by sharing Bicycle Day with your friends, family, and followers. Use the hashtags #BicycleDay and #BicycleDay2026 on social media. The more people who understand the scientific history behind this date, the better informed the conversation around psychedelic research becomes.
Related Awareness Days
- World Bicycle Day — Celebrated on 3 June, this UN-recognised day promotes the bicycle as a sustainable mode of transport and a tool for development.
- Mathematics and Statistics Awareness Month — Observed throughout April, this month highlights the role of mathematical sciences in everyday life and research.
- Cycle to Work Day — Held in August, encouraging people to commute by bicycle for health and environmental benefits.
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