Le Petit Bi
Frenchman Andre Jules Marcelin, inventor of the Le Petit Bi, first filed for patent on his bicycle in Luxembourg on March 23, 1938, it was issued on October 16, 1939. Then he filed for patent in France on March 22, 1939, which was granted on Jan. 1, 1940. He then filed for patent in Switzerland on March 21, 1939 and it was issued on Dec. 31, 1940. He also filed for patent in the U.K. on March 31, 1939 and it was issued on Sep. 25, 1940. Apparently he thought that the bike had significant commercial value or he wouldn't have gone to the effort and expense in filing all these patents. It is unknown who actually manufactured the bike and there are very few known to still exist, most likely because WWII broke out at this time and France became an occupied country. Below are the drawings from his patents. Note that he also envisioned a tandem and motorized versions.
The photos below are a version of the Le Petit Bi that differs some from the design in the patent filings. (Photos courtesy of the Embacher Collection)
The photo below is a different variation of the bike that has a separable frame that corresponds to the bike featured in the magazine ad shown below it. (Photo courtesy of the Embacher Collection)
Andre Jules Marcelin was a physics professor who worked with Jean-Baptiste Perrin at the Laboratoire de Chimie Physique (Chemical Physics Lab) at the University of Paris (Sorbonne). Mr. Perrin won the Nobel prize in physics in 1926. Mr. Marcelin and Mr. Perrin collaborated on a few non-bicycle related inventions since their names show up together on some patents. A photo of Mr. Marcelin with his physicist colleagues can be seen below.
The Chemical Physics Lab was known to hold seminars on Mondays at tea time where they invited writers, poets, and artists to speak. This may account for a couple of photos that are shown. The first is of Francis Picabia, a noted French painter, on a Le Petit Bi with his dog in 1940 and the second is of Jean-Paul Sartre, the famous French philosopher, in c. 1941. It's possible that they came to know Andre Marcelin through one of the seminars. The photo of Sartre is a bit intriguing since it appeared in a Nazi propaganda magazine called Signal which tried to show how normal life was in France during the occupation. Sartre had been in the French army but was captured by the Germans and put in a prison camp. He was released after only 9 months purportedly for medical reasons but it's possible he earned his release by agreeing to certain conditions, one of which was to participate, perhaps unknowingly, in propaganda activities. He given a teaching position shortly after his release, a fact which corresponds to a descriptive caption that accompanied the photo - "A cycling professor".
The Le Petit Bi wasn't Mr. Marcelin's first bike design, he filed a patent on August 7, 1935 for what looks to be a folding recumbent bicycle. Drawings from the patent are shown below. Fig. 1 shows how the bike compared in size to a full-size bike.
The Le Petit Bi may have influenced later small-wheeled folding bike designs. The first photo below is the Brompton prototype #1. The second photo is the Brompton prototype #2. Apparently Brompton ultimately found the design lacking since they ended up producing folding bikes with a quite different design.