Pulling over would have saved teen:inquest

If a teen on a petrol-powered mountain bike had stopped when police tried to pull him over, he would still be alive, the NSW officer who allegedly pursued him says.

"It's one of those circumstances where, I believe, if James had stopped we wouldn't be here," Constable Jacob Strzelecki said to the Ciappara family.

James's parents and grandmother were at Glebe Coroners Court on Tuesday as a four-day inquiry into the 14-year-old's death began.

He was killed in October 2013 after his modified bike crashed at an intersection with a Honda minivan and a Jeep at Miller, in Sydney's southwest.

The back brakes had been removed and the bike did not have lights or reflectors.

The court also heard James was not wearing a helmet.

Const Strzelecki told the court he tried to stop James by using flashing lights and a siren.

But after seeing James wobble and swerve, he said he backed off, believing a pursuit of the boy would be dangerous.

He then followed James about 40km/h - without warning lights or sirens - to see where he was going but said he was not pursuing him.

Earlier on Tuesday, the court heard all officers in Const Strzelecki's area had been given instructions on how to deal with petrol-powered bikes, which were popular with teenagers.

But he denied being given any such information and thought all modified bikes were illegal.

He also told the court he struggled to return to work at times.

Detective Inspector Darren Newman, who is in charge of the police investigation, said the two-stroke engines caused significant danger to riders.

"These motors are not meant to go on mountain bikes," he told the court.

They were banned in October from public areas such as roads, footpaths and parks, but could still be used on private property.

Det Insp Newman said the ban should extend to private properties.