The authors, with a clear-eyed sportsman's glee, and spared the uninitiated American's memories of early gangland movies and leather jacketed squadrons, have produced a beguiling book. All the twists and turns of evolving motorcycle innards, with an appreciation of contemporary models, will undoubtedly satisfy the buffs, but with a group of entrancing photographs and witty text, this may well draw some peripheral interest. The photos of early sportsmen, inventors and competitors in situ as well as a luxuriant display of landmark advertisements, tell the story for the novitiate. A turn-of-the-century quadricycle exhibits the Duke of Manchester cheerily taking a lap-robed friend for a spin; a dashing Harry Collier, founder of ""The Matchless,"" crouched over his machine in 1911; an ""anxious trio"" navigates a hill in the ""Side Car Interlude""--all recall an era of extravagant experimentation. The tale of roaring motors ends on a forward looking note, as the British authors look to a new burst of invention from America, a ""new age of emancipation and enlightenment."" A find for the sportsman-fancier; a bit too erudite for the helmet and iron cross crowd; but a reliable ""modern vehicle"" staple for the library.