When riding bicycle, safety is always at the top of the mind. I have a large convex mirror to see behind cars, and I wear a reflective safety vest (types that are worn by construction workers). One camera is mounted in the front to record the journey and safety, and the other one mounted at the back to record wrongful doings of motorists.
For the front camera, it is mounted on top of a 3 axis gimbal stabilizer to ensure smooth footage, as the handle bar always turns left and right and the shakiness of the bicycle during ride.
Here is an example of 2 cameras in use simultaneously that is video edited together.