Helmut Fath of Ursenbach began building racing sidecars in 1956, and Peter Kuhn began developing the URS engine, a DOHC 498cc four which produces 88hp at 12,800 rpm (and was good for 15,000 rpm) - far ahead of the competition. Fath was a veteran international road racer, and he won the world sidecar championship twice, in 1960 and 1968 - his second win was on the URS. He was also a keen IOM TT rider, competing six times and winning once.
Housed in a Metisse chassis from Rickman, the URS machines achieved many wins and podium places ridden by the likes of Paul Smetana, Karl Hoppe and Ferdinand Kaczor. Fath then teamed up with the Munch concern URS 500cc engines were used in Munch-URS GP solo racers. The partnership produced excellent results but was short-lived.
Horst Owesle and Peter Rutterford took the 1971 World Sidecar Championship on a URS, and a 750cc solo version appeared that year.
Some motorcycles were badged as Fath, for instance the Fath 500.
Sources: GTU Oldtimerservice, Gespann-Lexikon, Phil Aynsley, et al.
