! Warning ! Unpopular Opinion Ahead
If you gonna do it, go mirrorless. But, I would strongly argue to not do it. At all. It tends to take from the riding. The camera needs constant safety procedures and becomes the focal point (pun intended) of the enterprise.
There is such a glut of cliche bike photography bombarding us on every social media site it has become a mundane and banal pursuit to which even Andy Warhol has grown fatigued.