Buster Keaton is considered the best physical comedian of the silent era, thinking up and executing his own elaborate stunts, and directing himself in wildly popular films during the entire 1920s. His stone-faced expression, which subtly morphs from maudlin to curious to shocked, was a key to his comedy, being a total contrast with the outrageous action of his films. Keaton included some stunt riding on a 1923 Harley-Davidson 'J' model in the 1924 film 'Sherlock Jr.' Another scene in 'Sherlock' with a moving train and water tower fractured his neck, but didn't realize it until x-rayed years later. Keaton had an exceedingly long career, successfully making the transition to 'talkies' and then television. His last film appearance was 'A Funny Thing Happened on the Way to the Forum', in 1966, when he was 70 years old.
Larry Semon (below) was another talented actor/director/stunt man, nearly forgotten these days, but in the 1920s was a very successful and wealthy film producer. He's remembered today for directing the first, silent version of the 'Wizard of Oz' in 1925 (in which he played the Scarecrow), and for working with both Stan Laurel and Oliver Hardy, before they created their immortal comedy team.
Semon directed and acted in the short 'two reel' film 'Kid Speed', about two auto racers (Semon and Hardy) competing for the same girl ('Lou duPoise', a reference to the duPont family). Semon was known for his elaborate/expensive sets, sometimes building fully functional houses for a film, as well as huge gags - in the case of 'Kid Speed', an entire mountainside slumps onto a road for comic effect. If you want to skip the slapstick and see the cool old racers, jump to the 14minute mark (note - this video begins with an advertisement which lasts 30 seconds).
Semon's best motorcycle work is in this film, 'Taken For a Ride', in which he tries to impress a girl by stealing a ca.1922 Henderson DeLuxe with sidecar, with predictable results - his girlfriend knows more about the workings of a bike than her suitor. This short is a 'one reel' movie, ie the length of a spool of film; 12 minutes. 'Kid Speed' is a two-reel film, shortened to 18 minutes; this may be the result of deterioration of the original, highly volatile nitrocellulose film stock. Semon died in 1928 of tuberculosis, and many of his films languished in private collections before being rescued and transferred to more stable 'Safety Film' stock - cellulose acetate, which is much less flammable. Note the words 'Safety Film' on your old 35mm Kodak negatives; previously they would have had 'Nitrate' in dark letters printed. Nitrocellulose is explosive, derived from 'guncotton' and related to smokeless gun powder, and was the foundation of the DuPont chemical fortune.
Harold Lloyd was an actor/director on par with Buster Keaton and Charlie Chaplin, and more financially successful than either. He kept control over his image and his films, refusing in later years to allow distribution of his work unless for a very high fee...which meant that by the 1950s and 60s, his was slowly forgotten, unlike his rivals. Like other directors, Lloyd found that motorcycles added to the kinetic appeal of a chase sequence. The three-cop pursuit of Lloyd - riding two Harley 'J's and a Henderson 4 - in the 1920 film 'Get Out and Get Under', is a zany early car chase sequence. To see the whole chase, click here.
Board Track racers could expect a short career, and considered themselves lucky if they escaped without serious injury. Buster Keaton demonstrated how far stuntmen would go for a laugh in the '20s, while others did spectacular work as well; click here for an example, from an unknown film (sorry, I can't embed it). A 25' leap over a deep canyon on a 1920s motorcycle - serious business. Nowadays stunts are computer generated, and I can't imagine a contemporary actor putting him or herself in the face of such hazard. These riders were the real deal, 'The Artists' of a different calibre.