Motorbikes were a form of ground transport, typically able to carry one or two riders. They were common on Earth in the 20th and 21st centuries.
In October 1963, the First Doctor was almost run over by a motorbike driven by either a Mod or a Rocker in the East End. (AUDIO: Hunters of Earth)
The Monk's TARDIS briefly took the form of a motorbike when the First Doctor reprogrammed its chameleon circuit, ultimately changing its outer form to that of a police box. (TV: The Daleks' Master Plan)
In 1968, the Second Doctor rented a motorcycle and rode it to Surrey. (AUDIO: The Dead Star [+]Error: Code 2 - no data stored in variables, cache or SMW.)
International Electromatics patrolmen used motorbikes. (TV: The Invasion)
A number of UNIT troops used motorbikes. (TV: The Ambassadors of Death)
Captain Mike Yates borrowed an army motorbike to pursue Harry Mailer and his fellow inmates from Stangmoor Prison to a hangar after they captured the Thunderbolt missile. When the inmates started shooting at him, one of the tyres of the motorbike was shot and Mike came off just as it crashed straight into a pile of crates. (TV: The Mind of Evil)
Yates used a motorbike again to follow the Third Doctor and Jo Grant in Bessie when they were chased by Tom Girton in the UNIT helicopter in an attempt to drive them into Azal's heat barrier, which was surrounding Devil's End. To show Sergeant Osgood what was needed to penetrate the heat barrier, the Doctor used a felt-tipped pen to draw a circuit diagram on the motorbike's windscreen. The Doctor then used the motorbike to ride back to the village, as Yates had taken the injured Jo back to The Cloven Hoof in Bessie, but was shot at by Bert and forced to continue on foot. (TV: The Dæmons)
Ruby Duvall's father was hit by Michael Brack's motorbike; he ended up paralysed for the rest of his life. (PROSE: Iceberg)
Billy had a motorbike called the Vincent, which had a passenger sidecar. The Seventh Doctor drove it for some time during his encounter with the Bannermen. (TV: Delta and the Bannermen)
On Segonax, Nord rode a five-wheeled motorbike to the Psychic Circus. (TV: The Greatest Show in the Galaxy)
In Perivale, the Seventh Doctor faced Midge, who was infected with the Cheetah Virus, in a duel which involved the use of motorbikes. (TV: Survival)
On 31st December 1999, the Eighth Doctor and Grace Holloway stole a motorbike from a policeman in San Francisco while trying to get to the Institute for Technological Advancement and Research. Shortly afterwards, another policeman rode his motorbike (with faulty brakes) through the open doors of the TARDIS, immediately turned around, and sped off in the opposite direction in shock. (TV: Doctor Who)
Blaidd Drwg (Bad Wolf) was a motorbike gang. (COMIC: Jetsam)
Sarah Jane Smith used her sonic lipstick on a motorbike. It sparked and disorientated the rider. (TV: The Lost Boy)
Rory Williams and Amy Pond pursued their daughter Melody on a motorbike in 1939 Berlin. To do the same, the Teselecta was able to change its shape into a human riding a motorbike. (TV: Let's Kill Hitler)
The Doctor rode an anti-gravity motorbike in the 2074 Anti-Grav Olympics, an event in which he claimed to have finished last. A Spoonhead hacked into by the Eleventh Doctor used this motorbike to climb the Shard in London. (TV: The Bells of Saint John)
Clara Oswald later used the Doctor's same anti-grav motorbike for her commute from Coal Hill School. She had enough skills riding it that she could easily drive it into the Doctor's TARDIS console room and park it inside. (TV: The Day of the Doctor, The Magician's Apprentice)