I used my iPhone with a cycling app for over 4 years and never had any issues. I did, however, have a Wahoo RFLKT connected to the phone to display my ride data so I could keep the phone's screen turned off. When my RFLKT died, I went with a Wahoo Bolt and found that the battery drain, per ride, is the same as that of the phone. If you are charging the phone while riding, I don't see why you should have any issues. You may have to do some research on things that you can do to increase your phone's battery life, which should help.