Originally Posted by
Carbonfiberboy
This is pretty cool:
http://www.bandhayoga.com/keys_psoas.html
A riding buddy of mine had this problem. Solved it by moving his saddle a bit forward, lowering his bars quite a bit (3"?) and going to a slightly longer stem. The increased stretch seemed to relax the muscle.
I've been having issues forever with my left lower back hurting on rides. I had a fit that solved it and it started up again when I had to swap saddles after mine broke.
Over winter, I'll try flipping my stem down, and putting my saddles nose down a hair more and see if that helps.
Thanks!