Independent of bike fit, you might want to work on strengthening hips/glutes. Mine were pretty weak, and coupled with flat feet I’ve been living with biomechanical issues for 35+ years (post-college, desk jockey).
I’m not moving into my senior years without a fight. For what its worth, these are my phase 1 remediation exercises:
- side lying hip raise
- side lying clam shell
- side lying leg raise
- side plank
- bird dog
- leg raise
- glute bridge
- one-leg Romanian deadlift
- calf raise
- foam rolling to target piriformis
- internal rotation of hip to strengthen gluteus medius and gluteus minimas
A number of physical therapists post videos on YouTube, if you want to get started that way.