About 100 riders were taking part in the ride at about 1:30 a.m.
Alberto Bocanegra, Jr., known as a community activist who once ran for 12th Ward alderman, was in a car as part of the bike riding group and was recording the cyclists.
He saw a car hit one of the bike riders -- a 30-year-old woman -- and take off. Bocanegra raced after that car and got into an argument with the driver.
Then, a second vehicle -- identified as a blue SUV -- pulled up and someone from that car opened fire, shooting the victim twice in the neck.
Bocanegra was transported to University of Chicago Medical Center, where he was pronounced dead.
Bocanegra had recently battled cancer.
The female bike rider sustained a shoulder injury and was transported to Northwestern Memorial Hospital, where she is expected to be OK.
No one was in custody for the shooting Tuesday.
Police are investigating.