I have to agree with those that say putting your phone on your handlebars is a bad idea. But not (just) because of the value of the phone.
The biggest reason is that a crash that could take out your phone may also take you out.
The only thing worse than realizing that the crash just destroyed your smartphone is then realizing that you cannot call or text for help, nor do you have a map to get you out of there. Oh, and that bone sticking out of your leg is starting to really hurt...
Every time I see a person with a phone on their handlebars I give wide berth in passing. They tend to be, for the most part, novice riders and are more prone to unpredictable movements when encountering other riders. They also tend to spend too much time looking down at their handlebars, engaging with their phone. If I had a dollar for every time I "surprised" one with my bell when they came at me without noticing, I could actually buy that new Garmin I've been eyeing.
We all did fine for many years without a phone, put it in your pack and enjoy the ride. If you need a map, a cycle-based GPS is a really good idea.