The springs help. Lots. In those days EVERYBODY wore a 'Kidney Belt' to try to keep them in place against the pounding vibration. In all honesty, they didn't work very well. This bike had a horizontal dampner between the frame and the rear wheel that had to help enormously.

WWII was really good for one thing: Hydraulic technology made huge leaps due to the aircraft industry and it wasn't long and motorcycles actually had the hydraulic technology that we use today.

The first certified 100mph production motorcycle was the Triumph Bonneville of the late 40s. The model was named for the land speed record they set at Bonneville Salt Flats, Utah. Back in the day we called it 'doing the ton'. Hitting 100mph. My Connie will do it in 3rd gear with ease.