The most prestigious variants are the Alpine Grand Sports with a reduced compression ratio suitable for hill climbs, and the use of a JAP engine from JA Prestwich. A bike made in 1929 with all these features was sold for £ 315K including premium by Bonhams on November 30, 2014.
Another SS100 AGS with JAP engine made in 1930 is for sale on April 19 by H and H in the Imperial War Museum at Duxford near Cambridge. After two factory visits for improvements in 1931 and 1933, this bike has never been restored.
Made to order, this unit included options from the outset. It retains its 1930 Cruiser model sidecar. This configuration is extremely rare for the much sporting SS100 as the sidecar was essentially proposed with the SS80 road model. In 1933 its 3-speed standard gearbox has been replaced by a 4-speed box.
Motorcycle collectors are looking for authenticity but in the opposite to car lovers they enjoy an intense use. The SS100 AGS is sold by a former president of the Brough Club who acquired it in 1990 and piloted it in rallies throughout Europe. It is difficult to find better. It is estimated £ 280K, lot 42.
I invite you to watch the video shared by the auction house showing its operating condition (without anybody in the sidecar!).