Cyclists found to have killed or seriously injured a pedestrian will face penalties of up to five years in jail or a $68,000 fine, after tough new laws came into effect today.

"Cyclists need to recognise that, if they do occasion damage, they have responsibilities. They do need to stop,'' said Roads Minister Tim Pallas said, launching the new laws this morning at a Bourke Street bicycle shop.

The new penalties, he said, would help police tackle reckless riding by cyclists, and reduce the likelihood of pedestrians, other cyclists or drivers suffering serious injury.

"We're driving home to cyclists the need for them to obey road laws or be punished,'' he said.