"Big Bertha" 1928: a unique motorcycle designed for racing in the hills (7 photos)
Only 4 models are believed to have ever been made. Hillclimber Excelsior "Big Bertha", and only 2 of them are known to exist have survived to this day, and this motorcycle is the only one with original engine on original frame. 
Along with the advent of the first cars and motorcycles, there were people who liked to drive them. The rules were simple - who the first one arrived and won, but pretty soon the race on a flat surfaces bored many. Why not try to climb this thing uphill - one of the riders once thought ...
This is how Hill Climb Racing appeared, abbreviated as Hillclimbing or mountain race. Unlike motorcycle mountaineering, here are races against the clock, on relatively short route. Of course, no specialized motorcycles for such races were not produced, so each rider either modified existing models himself, or created his own cars. Big Bertha is one of those. 
In 1925, one of the most prominent motorcycle racers of those times, Joe Petrali moves to Excelsior, which presents him with their best creation - Excelsior Super X and unlimited access to design department to implement all their technical ideas. 
Taken as a basis, Super X is being finalized for mountain racing. Petali redesigns and strengthens the frame, front fork, big road the gas tank became useless, a small one was installed, which was enough for passing the track, but the main attention is paid to the engine. 
Two-cylinder four-stroke V2 is bored to a liter volume, the intake manifold and carburetor are also being finalized towards greater performance, increases the finning of the cylinder itself and the head cylinder for better cooling. Inlet valve diameter increased and improved exhaust cooling. 
The gear ratios of the transmission have been changed in the direction of increasing traction, by The drive wheel is dressed with a chain for better lugs. Here she is no longer original, but a copy of the one that stood in the 1920s. 
The exact number of "Big Berts" built by Petrali is unknown, whether three or four. 
