it’s called “bike & run tracker - cadence”
https://apps.apple.com/us/app/bike-run-tracker-cadence/id1490975634
on an iphone 13 mini, the battery lasts about 8 hours with 1/4 screen off, 1/2 on stats, and 1/4 on maps, using other apps, etc. i’ve done 100 miles without topping up, but for a ride...