= new reply since forum marked as read
Before I got a Garmin cycling computer I used an iPhone for tracking cycling data including speed, cadence and heart rate. An hour was OK but 2 hours was leaving very little battery left. I used a flat battery pack that was OK keeping it in my saddle bag with the cord run along the top tube. Then I found this.
https://smile.amazon.com/gp/product/B00B13A7CQ/ref=ppx_yo_dt_b_asin_title_o04_s01?ie=UTF8&psc=1
It can mount on the top tube just behind the head tube. It will keep your phone operational and fully charged. This image shows it mounted on the stem which was out for me because that's were the main junction for Di2 box is located.
You will have to buy the cord as well. The curly one shown is really nice.
https://smile.amazon.com/dp/B00FZM2VTG/ref=dp_cerb_2
And to anyone who cares I am not promoting Amazon. This may be found in local bike shops just not in the 4 in my area.
