So a phone app does everything, but you're just worried about your expensive phone? Get another. Search "android prepaid phone" they're mostly around $30.
Not to mention, phones overheat in direct sun and stop working. Phones' capacitive touchscreens are also completely unusable in rain, contrast to the physical controls on a cycle computer.
Cycle computers are much lighter than phones generally. Their mounts are more robust and aerodynamic. If you crash, you're very likely to destroy your phone, whereas cycle computers are generally fine unless you directly bash them into a rock. Cycle computers have configurable high brightness LEDs for navigation cues and other training specific data display like HR or power.
Ok rant over. Mumble mumble Chesterson's gadget. If one doesn't know why it exists, maybe ask why...
To save me some buck I strapped an old sport watch to the bike, it can connect to everything, last days on a single charge and it has physical buttons. Just as good.
Varia alerts don't utilize the screen, they are just buzzes and beeps. A phone will last for days with screen off, especially with no sim card. They asked for the cheapest option.
It's tempting to think that phones can do everything, and they sort of can, but not well. There's a time and place for dedicated hardware, and cycle computers are very firmly in that category, aside from very casual usage.
I think they meant that the vibrations mean the app doesn’t work because with the vibrations of the camera the picture is useless, not that it damages the phone.
