*stipe wrote:
Consult previous results. Find out roughly where 2:40 will place you. That time will get you top 10 or even top 5 in a lot of smaller marathons. So when 30 guys go out ahead of you and you are running 6:00 pace, don't get pulled out too fast. Those guys will come back to you. My last marathon was a 2:40 with a 1:50 negative split. Moved from 25th to 10th in the second half. If it is a bigger race, you should have some company to work with you and help with the pace.
Yes, whatever your goal place is, add some to that and start out in that position. This is partly because so many people positive split, but also because it is always more fun to pass than get passed (or to run alone). When you see guys who thought they were faster coming back to you, it's a great feeling. Everyone you pass in the second half is a boost of energy.
It is hard to hold back to proper race pace at the beginning. The first few miles feel like a Sunday long run to me. It is much unlike a 5k/10k/half where you're already working hard 1/3 of the way into it. You run into a different "limit," you might not feel like you're breathing hard at the end, but your legs hurt.