THink of your spine as a flagpole with many wires attached from top down to the ground to keep it standing straight. If several of these wires (analogy: hammies, psoas) are too tight, they cause an imbalance, and the other wires (analogy: your lower back, core abs, obliques, etc) have to work harder to bring the flagpole (analogy: your spine) back into balance.
My approach was to implement a daily stretching routine, the use of a hard foam roller ($20-$40 at sporting good stores) to break apart knots/spasms, and core-strengthening exercies. I also selected a few stretches I could do on my rides and try to do them every 45-60 minutes when riding.