I've been using my phone as my bike computer for years. I currently have an iPhone 16 Pro, but most of my riding has been done with an iPhone 11.

For apps, I've used both Cyclemeter and Ride with GPS. They each have their pros and cons. In both cases, I keep the screen dark mostly, and rely on periodic spoken updates through a bone-conduction headset. One con that they share is this: I've got them set up to report at 15-minute intervals my average speed and heart rate for the whole ride, and for the last interval. One of these two sets of data—probably the last 15 minutes—is usually but not always wrong. This is obvious when it is exactly the same as the data for the entire ride. I first reported this bug years ago. Anyhow, relying on spoken updates lets me get easily 12 hours of battery life out of my phone. I usually have it hooked up to my dyno hub via a USB adapter, so battery life isn't a concern anyhow. Rainy weather is the one exception: iPhones disable their port in the presence of water, so for an epic ride in the rain (which I've done!), it is possible to run down the battery. The solution to this is to carry a power bank with a built-in Qi charger (which I wasn't doing at the time).

I feel that no app really takes full advantage of the possibilities that a smartphone could offer for data visualization. My dashboard shouldn't look like a miniature spreadsheet.

I've written extensively about different mounts on my blog. TL;DR: Peak Design has the best mount/case that I've used, Quad Lock is very good; Quad Lock is better for people who want to customize their setups, because they've got a highly modular system and sell the parts a la carte. That's what I'm currently using. I've got a mounting deck that I designed and had fabricated by SendCutSend, which fits between my aerobars, and can accommodate multiple lights and other gadgets.