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« on: October 22, 2018, 12:36:30 AM »
Alan,
Sloping top tubes were experimented with in either forward slope or rearward slope.
Most racing bicycles of this era had forward sloping top tubes to allow the handlebar stem to be as low as possible coming out of the steering head as the racer was tucked down to lower his/her center of gravity and also to get his/her body in a position for maximum leg strength to push the pedals via pulling against the handlebars for every pedal leg exertion. The shorter stem provided a more ridged feel for leverage from the rider's arms to transmit to his legs. forward sloping top tube frames are also better for high speed riding as a racing bicycle would experience.
Rearward sloping top tubes, as the bicycle you picture, allowed the long distance or pleasure rider the same advantage of a shorter handlebar neck for the ridged feel and also more frame mass forward to handle road conditions such as potholes, dips and rough surfaces encountered. Rearward sloping top tubes work better at medium to slower speeds. Just look at a modern trials off road bicycle or motorcycle which is at home doing 0-15mph as everything is angled rearward to keep the center of gravity as low as possible for balancing these specialized machines.
Handling would differ from a level horizontal tip tube bicycle frame via the less ridged longer handle bar stem letting the frame wiggle a little more due to the stem's flexing and torqueing somewhat.
Hope this helps.
Mike Cates, CA.