It is very handy to have a smartphone mounted on your handlebars while bicycling. You can run a GPS tracking program, play music, and even take a call. A diversity of mounts are available to buy for this purpose, but many are quite expensive, while others are woefully inadequate. I actually purchased a fairly nice ball-and-socket type phone mount and it broke on the very first ride. I was fairly anguished while watching my phone bounce down the road behind me. After puzzling on the problem for awhile, I came up with a simple, elegant solution.
Smartphone holster and case
I already had a holster that I liked, made by the popular OtterBox® company (but this is not an endorsement). Part of what made this project work was that I got a spare one from a friend who had changed to a different type of phone case. Thus, I was able to mount one on the bicycle semipermanently, while keeping the other for normal, daily use on my belt. I could then snap the phone out of my hip holster and right onto the bike and vice versa. I'm sure a variety of such holsters would work, and with some research, you might find a second one the same as your own in good used condition for a cheap price. With this system, you can easily pop the phone out to take a photo as well.