I make up a pace card with two columns based on my expected finish times. It gives me an idea of how I am progressing along the course. It is wise to heed Matt's advice in the footnotes of the Pace Calculator regarding loosing time if you have not done training at altitude. The race becomes increasingly more challenging with increasing distance and altitude so it is good keep something in reserve. Last year a female entrant(one of the favorites) who consistently runs several marathons a year under 2:40 could not maintain a pace of 26 minutes/mile for the final three miles above timberline.
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Thanks for the link. I wish I could run that fast.