"Keystone" or "Marion" Motorcycle Frame

In 1919, Indian debuted its challenger to the Harley-Davidson IOE  (intake over exhaust)  racers that had dominated American race tracks since 1915.  The new Indian challenger was a side-valve derivative of the famous Powerplus which, after its record-setting speed trials in 1920, became known as the Indian "Daytona."  The 1919 Indian racer that appeared at the Marion,  Indiana Labor Day race featured a  "keystone"  style frame;  henceforth,  Indian's version of this style of chassis was known as a "Marion frame."

Harley-Davidson pioneered the use of the "keystone" frame in their successful 1916 win at the Dodge City, 4th of July 300-mile race.  The keystone frame was actually a modified loop frame with the bottom of the loop cut away.  This allowed the engine,  supported by plates,  to act as a structural member of the chassis.  Although Harley-Davidson's success at the 1916 Dodge City race was due to various innovations  (8-valve engine and hemispherical combustion chambers, for example),  the improved handling characteristics of the lowered engine position prompted Indian to follow suit.

Due to the likelihood that the United States would become involved in the European World War,  all of the major motorcycle manufacturers withdrew from professional racing in the Fall of 1916.  In 1918,  with the end of the war in sight,  Indian modified one of their existing loop-frame 8-valve racers to the "keystone" configuration.

In addition to the new side-valve racer that the Springfield manufacturer debuted at the Marion race in 1919,  Indian continued to field a number of their previously successful 8-valves that had dominated the board-track and publicity-rich speed trials in earlier years. Now,  however, the Indian-8's were installed in keystone chassis.  On one such bike in 1921,  Albert "Shrimp" Burns won the pole position at the Dodge City classic by setting a lap record of 97 M.P.H.

Copyright ©1996 Daniel K. Statnekov
Installed:  April 12, 1997
Revised:  June 28, 2003