The Blaze Laserlight trial involves 250 Santander Cycles for hire, with the front light built into the frame.
It aims to increase cyclists' safety by giving them a bigger visible footprint and to overcome drivers' blind spots.
There have been eight cycling deaths in the capital this year, seven of which involved heavy goods vehicles.
Critics say dedicated cycle lanes would keep cyclists safer.
Santander Cycles said the trial was being funded as part of its annual budget and if the trial was successful it hoped to extend the laser light technology to more of its bicycles.
A light that projects a bicycle symbol on the ground 6m (19ft) ahead of cyclists to make them more visible to drivers is being tested in London.