Which motorcycle did Brough Superior advertise as the first production bike guaranteed to reach 100 mph?

The Brough Superior SS100 was advertised as the first production motorcycle guaranteed to reach 100 mph.

George Brough introduced the SS100 in 1924. Its name referred to a claimed 100 mph performance standard, and each motorcycle was tested before delivery. The model used a large V-twin engine supplied by JAP or, in later examples, Matchless, rather than an engine designed entirely by Brough Superior.

The SS100 was built in small numbers and marketed as a luxury performance motorcycle. It is often confused with the Brough Superior SS80, whose name referred to an 80 mph guarantee. The SS100's reputation also grew through the ownership of notable riders, including T. E. Lawrence, known as Lawrence of Arabia.