There's concern even quad bikes designed for children are too much for youngsters to handle.

It comes in the wake of a six-year-old girl dying in a trail bike accident in Masterton over the weekend.

Child and Youth Mortality Review Committee Chair Doctor Felicity Dumble says even vehicles that are considered size-appropriate can be dangerous.

"We do know there are issues for those under sixteen in terms of their physical size and strength and being able to actively ride these vehicles," she says.