Hundreds of cyclists were arrested on Friday night after trying to take part in a Critical Mass event. Critical Mass takes place every month and has been going for eighteen years however on this occasion police clamped down heavily to prevent the cyclists from taking the intended route and the evening ended in serious violence and mass arrest.
In the first few seconds of this video British Transport Police Officer 4125 is shown grappling with a man in a Shopmobility scooter, and then aiming something at him. (Probably CS spray.) The man shouts several times “I am disabled” but is ignored. A police medic can be seen trying to wrestle him away and prevent him from using it. Further in at 1:06 he can be seen and heard striking someone with a baton.

Trying to use spray

Baton strike - the rebound
The person who uploaded the video has written this account:
27th July 2012 19:30pm In the early stages of the Monthly Critical mass Bike ride a British Transport Police Officer PepperSprayed a Disabled Man in a shoprider who had been apparently hit by a car along with several others. During the melee as the officer is pulling out the pepper spray , A fellow Female police medic attempts to stop the action, but is struck back and the officer sprays the Disabled man and most of us in the crowd, not satisfied, he then whips out his telescopic truncheon and trys to apply a wrist lock / neck Lock on the Disabled man using the truncheon. Eventually a real Police officer arrives with 3 vans and about 50 Backups. The disabled man is arrested and the British Transport Cop is led away by some other officers. 27th July 2012.
From earlier in the evening:
FIT are filming #criticalmass from the top of waterloo bridge twitter.com/IzzyKoksal/sta…
— Izzy Koksal (@IzzyKoksal) July 27, 2012

FIT recording Critical Mass. Photo by @IzzyKoksal
Critical mass goers! Police are stopping all cyclists going north over the river @occupylondon
— Not Vicky Kapoor (@hrsyofgrmnghst) July 27, 2012
RT @jasonnparkinson: Police have banned #CriticalMass from north of Thames, section 12 public order act. twitter.com/JasonNParkinso…
— Therezia Cooper (@ThereziaCooper) July 27, 2012
I love it how an 18 year old monthly bike ride has suddenly become an issue of national security #London #CriticalMass
— brixton hatter (@BrixtonHatter) July 27, 2012
a couple of metres away from the Olympic ceremony - there are over 50 police vans and thousands of police kettling cyclists. #criticalmass
— Izzy Koksal (@IzzyKoksal) July 27, 2012
View from inside @MetPoliceEvents kettle of #criticalmass. Photo by @OurOlympics
#criticalmass arrest buses - Photo by @indyrikki
Seems like people being taken 2 Leyton in a prepped Olympic detention camp - only processed at stations first #openingceremony #criticalmass
— Aaron Peters (@aaronjohnpeters) July 28, 2012
Soldiers are assisting police taking people to holding centre #openingceremony #criticalmass
— Aaron Peters (@aaronjohnpeters) July 28, 2012
Regular London bus drivers being used to drive arrestees to Leyton, just chatted to one #criticalmass #openingceremony
— Aaron Peters (@aaronjohnpeters) July 28, 2012
Update
Here is the event shown in the video above from a different angle.
Bail conditions imposed on those arrested:
Been informed 20 #CriticalMass sat on concrete floor of Croydon police garage for 3hrs, arrested for 12 hrs, not been given legal access.
— Jason N. Parkinson (@JasonNParkinson) July 28, 2012
News Coverage
BBC: Arrests made at mass bike ride on Olympic Ceremony night
ITV: Protesting cyclists ‘detained’ (Lots of pictures)
Guardian: Critical Mass cyclists arrested near Olympic Stadium
More Information
Critical Mass London
Guardian: Critical Mass police ban blocked by law lords - 2008 article. Critical Mass ruled lawful and attempts by the police to ban it were overturned.