Compact size, bike computer is much more convenient, it weighs less, smartphone is much more larger.
Battery Life, it can last months vs apps that can last 3 hours using gps, If I were you I would rather save it for a real emergency. Your phone will still be useful as a phone, it’s linked to battery longevity again but seriously, when you’re out on the road you never know what’s going to happen and you need to retain the ability to phone for help, should the situation arise.
No recurring costs
Save your data allowance and you won’t have to pay any data fees.
The smartphone is important to our personal and professional life. So, having it destroyed in a bike crash would not be good at all. I wouldn’t risk my iPhone anchored not so safely to my bike, and less if suddenly it starts to rain cats and dogs, which leads to another problem… I would choose a waterproof bike computer that stays on the bike instead.
If you are lucky and the sun is shining, then you won’t even see clearly the screen because of the sun. Most cycling computers are easier to read in direct sunlight. And let’s be serious, smartphones are not designed to sit out exposed to hot sun, extreme temps, and rain; all of which commonly occur in serious cycling.
Easy of use
Ease of use, easier to mount, my bike computer was specifically designed to sit on the handlebars with easy access to most all functions and in typical cycling conditions. The smartphone is not. I wouldn’t even want to risk my phone in one of those things.
Some smartphone/app combos have questionable reliability. App crashes or flakey background functionality can leave you with big gaps in your data logs. It’s not always bad, but i’ts unpredictable and you want better than that.
Compatible with gloves
Touchscreen phones don’t like gloves. Screen works with gloves on in bike computer. Very handy in winter! It is such an annoyance to have to take a glove off to operate the phone, particularly if it’s really cold.
Affordable price compare with dedicated bike computer, cheap enough to leave on your bikes in most of places. If you’re a casual bike rider, consider using a bike computer, and put that extra money toward more cycling gear, than buy a dedicated bike computer with gps, which can be quite expensive, like Garmin’s ones.
Bike computers are a simple and effective way to gather data about your rides and training sessions. They can help improve your practice, track your progress and are also fun to use. If you’re serious about improving your cycling, you should consider buying one. Have a faster progress, compete with yourself, and analize data, its fun.