Hi all,
I've been doing research on this to the nth degree cos I've been getting some niggles, so I'm happy to share what I found out. The first thing is to be careful of what you read on the internet! It can be scary.
Anyway, between talking to my physio and various other people, there are three causes of tight ITBs in cyclists:
1. Poor equipment
2. Biomechanical problems ie excessive foot pronation
3. Poor training regime ie sudden leap in activity level
I have addressed all of these to try and eliminate all the causes. I'm not guilty of 3, so I checked out my pedals and cleats. The cleats were extremely worn and there was movement in the pedal axles, so I bought new ones. I then went to see a podiatrist (at leicester sports medicine clinic) - well that was amazing. I was astonished to discover that my feet don't work properly at all. Without going into the detail, they need radical orthotics. He put some together and the difference is amazing. There's now much less pronation.
In addition to this the physio has given me a really comprehensive range of stretches to lengthen out the calf muscles, which were also tight, and stretch the ITB (this is called the 'Thomas' stretch, which you can look up on the internet). It's all working really well and I managed a big ride last Saturday with hardly any pain at all.
So there!