I use the bar clamp style one for rear shots from the seatpost and have this one for out front for my Garmin and GP all in one http://www.amazon.com/K-EDGE-Garmin-Computer-Interface-Cameras/dp/B00OC7ESOQ/ref=pd_sim_sbs_422_1?ie=UTF8&dpID=31aEF-Yb6bL&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&refRID=0VMCZ75SB003BCKV0F1N
There's a threaded bolt under the Garmin mount for a GoPro or other device (I also put a Light & Motion front light there during winter training).
https://www.amazon.com/K-EDGE-Garmin-Computer-Interface-Cameras/dp/B00OC7ESOQ