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Pure Excellence
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Excelsior 7SC
Ray Thursby
03/01/2006
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Photography by David Gooley
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On the third day of December 1912, a motorcycle officially
broke through the 100 mph barrier for the first time. Within a matter of days,
the same machine, a 2-cylinder Excelsior piloted by Lee Humiston, established
new FIM speed records for distances of two to 100 miles during a run that lasted
just over 68 minutes on the one-mile track at Playa del Rey, Calif.
The bike
used in that feat was very similar to the 1914 Model 7SC seen in these
photographs, one of many racers that came from Excelsior’s Chicago factory. By
the time the 7SC was built, the company had a firm reputation for building fast
competition bikes and solid, reliable road machines, as it would right up to the
day in 1931 when production ceased.
Though it is taken for granted today that
virtually any motorcycle will top 100 mph with ease, riding one of these bikes
at speed must have been a daunting experience, whether in a run against the
clock or eager competitors. There are, as is readily apparent, no brakes of any
kind; nor is there any provision for shock absorption, save the flexibility of
frame and wheel spokes and the horsehair padding in the leather saddle.
At
least one rider with experience on such bikes claims they are not that difficult
to ride. He avers that one must be “tucked in,” which is to say leaning as far
forward as possible over the dropped handlebars to keep maximum weight over the
front wheel. After that technique was mastered, all that remained was to steer,
work the throttle, occasionally operate the manual oil pump, keep an eye out for
other racers, worry about dust or splinters—from dirt- or board-surfaced
racetracks, respectively—and hope that the glue, shellac, or spikes applied to
the narrow tires’ beads would prevent them from coming off their clincher-style
rims.
 The 1914 Excelsior 7SC’s 61 cu in engine was not mated to a transmission. (Click image to enlarge)
By the standards of their time, Excelsior motorcycles were not
particularly innovative. They adopted a common frame design derived from
pedal-bikes, and indeed still had crank-mounted, bicycle-type pedals for the
rider to push for starting and to rest his feet on while riding. To minimize
weight, the latter feature was often removed from competition machines. This
particular example is slightly unusual in still having its rotating pedals and
separate starting chain.
The engine, too, is somewhat unremarkable. Like many
such powerplants of the day, its two iron cylinders, mounted on an aluminum
crankcase, displaced 61 cubic inches. The valves are laid out in the F-head
pattern: intake valves, operated by a long pushrod and rocker arm, are
conventionally located atop the cylinders, while the exhaust valves are within
the barrel and face upward. The engine’s 7 hp output was transmitted through a
clutch, but no transmission, to the drive chain.
For $250, the 200-pound
7SC—the name standing for 7 bhp, short-coupled frame—Excelsior was a worthwhile
investment for racers. It was purpose-built for speed, sharing few components
beyond basic engine castings with its road-going kin. With a good rider, it was
competitive straight from the factory, although there were a few modifications
that could increase speed. One such change was a hole, drilled at a precise
location (as spelled out in a bulletin from Excelsior) in each cylinder barrel,
to allow exhaust gases to flow out when the piston reached the bottom of its
stroke.
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