Marcel Duchamp’s Bicycle Wheel

Almost a century ago, the artist Marcel Duchamp put a bicycle fork and wheel on top of a stool in his studio. He said it was something to look at, like flames in a fireplace. When you spin a wheel with shiny spokes in a light you get a wonderful rhythmic sparkling display.

QUESTION 1.

What kind of visual effect can be seen in such a spinning wheel?

QUESTION 2.

How many official copies have been made and signed by the artist?

QUESTION 3.

What is a the major difference in these official copies?

BONUS QUESTION:

What feature of the bicycle wheel is most often not mentioned?