The cyclist in the incident was a 56-year-old Menlo Park man who was taken by medics to Stanford Hospital with possible fractures in his pelvis and sacrum, said Lt. Ray Lunny of the San Mateo County Sheriff's Office.
The cyclist, who gave an account of the incident to sheriff's deputies, may have lost control of his eastbound bicycle after a westbound vehicle of unknown make made an illegal turn and crossed the lane in front of the cyclist and headed on to the I-280 northbound off ramp.
The rider braked and went down, Lt. Lunny said he was told.
As to the fate of the driver, nothing is known. The driver may have realized the error and simply turned into the northbound lane upon reaching the freeway, Lt. Lunny said.
If there were witnesses to this incident, they have not yet come forward and are asked to contact Lt. Lunny at 363-4049.