For what it's worth here's my experiences. I used to run @10 years ago, back when I were a youngun in durham and I never had any ITBS, then after I starting biking and returning to running, whack I had ITBS. I suffered really badly for one marathon, then two great north runs.
I'm now ok. What's changed? I dropped my saddle, stopped wearing firm riding shoes, ride mostly in flats, moved my saddle further forward, so my knees are further forward. I have been told by several physio it's mostly caused by over development of one glute(sp) over the other. I think I needed to build up the poorer muscle, stretch more, that helped most. It may also mean your gait is slightly out and you will just learn to deal with it. I doubt how much the ice and physio work actually helped in the long run. They seemed very good at taking my cash though. Buy a good stretching book, I work with an ex physio who lends me one. Let me know if you want the title etc…