With a few exceptions, the majority of makers from the pioneer days and into the 1920s revised, developed and strengthened what were essentially developed cycle frames. A common form involved two, usually parallel, frame tubes with the fuel, often with oil compartment, fixed between them. There were of course exceptions to this concept, including ladies’ motorcycles with dropped frames, and occasional machines – often lightweights – with a single frame top tube from which the tank hung.
These designs made for tall motorcycles. Even those with long legs struggled to reach the ground with both feet when sitting on the saddle, and shorter riders needed to hop off and on at halts.
An early modification was to mount the rider’s saddle on a horizontal tubular extension of the frame’s top tube. A variation of this design was to create an extended ‘S’ shape in the tube and behind the main frame. Neither solution was satisfactory as they pushed the rider’s weight too far back on the motorcycle, making the back wheel carry more than its fair share of weight and over-lightening the load on the front wheel. This adversely effected steering, stability and handling.
As discussed previously, the solution was to curve the tail of the top tube downwards to a lug serving both top tubes, so lowering the saddle height.
Into the 1920s this concept was tweaked but largely unaltered and worked well with side-valve engine designs. But as soon as OHV cylinder heads were involved, engines became taller, leading to difficulties accommodating these longer engines. Some frames became necessarily high,
