On a few of my bikes I feel as if my shoulders are ‘shrugging’ up round my ears and I become uncomfortable after a time and sore the next day. I’ve experimented with bar height, saddle position/height and tried a lay back post to ‘stretch’ me out more. No significant improvements. I’m 5’11 with average leg length but I’d say longer than normal arms. My bikes are all in the ‘medium’ type range. Any ideas as to what I could try to increase comfort?

Try rotating your controls so they are horizontal,which will then rotate your wrists.I did this and found it helps.

Have you tried a longer stem? A cheap longer frame? Wider bars?

Stem is too long. Try dropping a cm or two. Assuming it’s a road bike, you are keeping your hip angle constant and moving your arms too far forward. The other solution, which is harder is to practice bending over further. A shorter stem is the solution for most people, but flexibility and stronger core can help with a more aero position as well.

I suffered from exactly the same problem and swapping from a 120 to 100 stem cured this immediately. If you need to go below 80mm for a medium sized road bike, your frame is too small