I actually found this issue to be MUCH worse on flat bar bikes. I had to switch commuters for this reason? I do a lot of stretching and looking around on the bike for the reasons you mentioned. I've got back to doing Yoga within the last month. While my back feels awesome my traps are still firing up :-( It's wierd cuz I feel like someone punched me in the arm a little below my deltoid after these rides too. It's so darn frustrating. I'm noticing it more this week bc I cracked 200 miles this week.