Hi @HappyMapper,
You can get a free mount for your bike from here - https://shop.mapillary.com/ which will get you started. I now use a GoPro Hero 7 Black for all my car capture and have it on a fixed mount that has been adapted from GarminVirb mounts. This is after trying a few cameras - Garmin Virb (not recommended), Virb XE (better but still had issues), Contour Plus 2 (low resolution).
If you were considering multiple cameras then be aware that GoPro app can only control ONE camera running time lapse images, but multiple for video which means more processing before uploading. I believe multiple Sony cameras can be controlled from a single app/button.
This thread has some great images of various approaches for vehicle mounts
http://mapillary.trydiscourse.com/t/experience-with-mounting-a-camera-outside-a-car/134/1