Silas Goldsworthy, a Scottish track champion and record holder, and Martin Williamson a former Scottish and British Championship medal winner, are the latest big names to join calls from the Road Share campaign for presumed liability to be introduced.
More than 6,000 people have signed an online petition backing the campaign and calling for a change in the culture of road users.
Mr Goldsworthy, 27 from Edinburgh, said: "Taking to the roads on a bike is significantly riskier than getting behind the wheel. I cycle all over the countryside as part of my training regime and for leisure and I have been involved in numerous 'near misses' as well as a couple of minor collisions."
Mr Williamson, who has been racing since the age of 12, said he commutes to Edinburgh most days and worries that "people are in too much of a hurry".