Bayerische Motoren Werke displayed their first motorcycle at the Berlin Automobile Show in September 1923. BMW's first "across the frame" version of the boxer engine was designed by Max Friz. The R37 is the bike which established BMW's racing heritage in its first year on the racing scene, and it is also one of rarest of the breed. When released in 1925, it was the first motorcycle anywhere to be powered by an engine with aluminium cylinder heads. The light alloy heads and overhead valves helped double the horsepower of BMW's existing twin of the same capacity and it took the BMW to the front of the pack in European racing. BMW racked up 91 European race wins in 1925, 105 in 1926 and 171 in 1927, winning the 500cc German championship title every year to 1929.