Motorcycling's governing body, FIM, has announced a change to the age limit to compete in the world championship from 2010.
Currently, riders can start competing in the 125cc category at 15, but FIM has announced the age limit will increase to 16 in two years' time.
The limit for 250 and MotoGP will remain unchanged at 16 and 18 years of age respectively.
"Sixteen years is the right age," MotoGP rider Loris Capirossi, the youngest ever world champion at 17, told Gazzetta dello Sport.
"When I won the title I had already done two years on real bikes in the Italian and European championships. I was young, but I was experienced.
"You can't push these youngsters like that: they win their parish church championship and then come straight to the world championship. Unfortunately I visit the Clinica Mobile and I see these kids there, maybe with some broken bones.
"We started talking about this last year in the Safety Commission with Valentino Rossi. Other riders, like Hayden and Pedrosa, agreed too.
"I don't think anyone can be against something like this, because if they start too young they risk getting burnt. And after all, at 16 years of age, they have a lot of time ahead of them."