i just tried to fit myself then using the youtube posted above - its raised more questions than i had previously!
the clip suggests that for my height i should have crankarm legth of 170 or 172.5 - i've only got 165mm cranks. but i took a photo of myself on the bike and i seem to have the right extension (even though when i ride i feel like i'm not getting enough extension in my legs). i'm concerned about going to longer cranks as i already have a fair bit of toe overlap. does anyone have this issue? good old sheldon brown seems to think 165mm is good for track bikes (although i don't ride on the track).
the other thing is that when i'm on my bike and i look down at the front hub i can see it over the handlebars (the clip suggests that the bars should obscure the hub). what is the solution here - longer stem or move the saddle back? I'm pretty sure my saddle is back as far as it goes.
so maybe i should go back to my original question - should i go somewhere to be professionally fitted?