According to the Old Rhinebeck Aerodrome web site:
Excelsior Motorbike (1913)
Chicago, Illinois U.S.A. The Excelsior Supply and Manufacturing Company was the biggest factory to produce Excelsior motorcycles and was part of the well-known Schwinn Bicycle Company. Excelsiors were produced in the U.S.A. from 1908 through 1931 when Ignaz Schwinn decided to discontinue manufacture of motorcylces. This motorcycle was donated by Paul Richards of Poughkeepsie, New York.
Taken with a Sony RX-100 M3.