The Special Investigations Unit says they are investigating an incident in which a cyclist was tackled to the ground by police during a traffic stop on Queens Quay.The takedown — captured on video and widely shared online — occurred on Sunday, May 31, near Queens Quay West and Little Norway Crescent, where Toronto police were conducting a stop‑sign enforcement blitz.The near-one-minute clip, posted to X by cycling advocate David Shellnutt, shows two officers forcefully bringing a cyclist to the ground as bystanders react in shock. In the video, the cyclist can be heard asking, “What did I do wrong?” while an officer responds, “You didn’t stop.”Toronto police have said the cyclist failed to stop at a posted sign, swore at officers and attempted to flee before being arrested and issued three provincial offence notices.In a statement, Shellnutt said Thursday his client was not assessed or treated by officers at the scene, despite having an “obvious head injury” after being tackled off his bike.“Our client has been diagnosed with a head injury/concussion and given a referral to a head injury clinic,” Shellnutt said. “His concussion symptoms remain ongoing.”The SIU confirmed Thursday that they had invoked their mandate.The unit is an independent government agency that investigates the conduct of police officials that may have resulted in death, serious injury, sexual assault and/or the discharge of a firearm at a person.