I use TrainerRoad on my phone. I just upgraded to the iPhone X and I need to find a mount to attach my phone to the Alpha X setup. I would love to have my phone centered between the bars, but I don’t see a mount on Amazon that would allow me to do that. My hands are very narrow, so the phone would unlikely fit between the bars and would have to sit on top.
I epoxied a garmin quarter turn mount on my other phone, but I have a life proof case on this phone and don’t plan on taking the case on and off.