Catrin, I have to agree with MP on the mental aspect of long rides. I am training for a mtb 100km event & whilst wind won't be an issue..The ability to keep mentally fresh after 60km to do 10km of really tech singletrack is. For me, it's the exact timing of my nutrition that matters.

No matter what you do to prepare, think about how you'll push yourself through the wind or whatever.

Keep up the good training work!

I'm doing a 200k the weeend after yours...(Trekhawk possibly too..)