Here is a convenient fitness mount that lets you easily attach your iPhone to your exercise equipment. The Belkin Exercise Machine iPhone Mount with MagSafe can be attached to treadmills, spin bikes, and elliptical machines. It is designed to work with iPhone 12, 12 Pro, and other similar models.
This iPhone mount works with cases up to 3mm in thickness. It can be used on handlebars and poles from 1 to 1.5″. It can magnetically attach to gym surfaces.