The alleged disruption came after two adolescents were killed in an e-bike accident.
The crash claimed the lives of Kyrees Sullivan, 16, and Harvey Evans, 15. No additional vehicles were engaged, according to the police.
Minutes before the collision, a South Wales Police van was seen on CCTV seemingly following the youths.
The police watchdog, the Independent Office for Police Conduct (IOPC), was then contacted by the force.
31 people have been charged in relation to the disorder that ensued after the incident on Snowden Road on May 22 at approximately 6 p.m.
Kyle Telemaque, 19, of Ely, entered a guilty plea to two counts of rioting.
18-year-old Jumana Fouad of Ely entered a guilty plea to the riot charge.
Ely resident Callum O’Sullivan, 23, showed up in court but chose not to enter a plea.
The first set of defendants to enter a not guilty plea to rioting were Jamie Jones, 23, from Llanrumney, Michaela Gonzalez, 26, from Ely, Jayden Westcott, 20, from Ely, and Lianna Tucker, 18.
Also entering not guilty pleas to the allegation were Luke Williams, 31, of Ely, Connor O’Sullivan, 25, of Caerau, Zayne Farrugia, 24, of Caerau, Lee Robinson, 27, and Jaydan Baston, 20, of Caerau.
