Rambling the Front Range of Colorado and Beyond
A lot of variables in there old bean, but I bet the second 50 of most people's 100 mile races are a minimum of two hours slower on average.To answer your actual question, and supposing no major issues on the back half: 50 mile time x 2 + 3-4 hours. So, a seven hour 50 would equal a 17-18 hour 100 over similar terrain. My highly scientific formula above is based on the assumption that you run the first 50 at approx 1 min per mile slower than 50 mile pace, and then slow on the second 50 by 2-3 hours.
Thanks, that sounds very close to what I was estimating.And, answered my other question I was thinking about of how much split on the 2nd half.Since your 10k->Towers algorithm works, I'm gonna go with it!
I would probably agree with Nick's formula. Although, I would say take the time you ran the first 50 of the 100 in and multiply it by 2 and add a few hours. From 100s that I can remember my splits they are something like 7:30(18:40), 8:30(19:30), 12:15(30:18) for the 50(100). So that relation generally holds true - the last one excluded due to a few problems...My point is that to go from 50 to 100 you should take the 50 mile time and add some time to get the 50 mile split and then double that and add some. I don't know about the 1 min/mile slower thing since that would mean a 17-18 hr 100 is something like a 6:10 for just doing 50 miles. I would say for front of the pack it is more like 30-45 sec/mile while further back 1-2 min/mile slower. I would also guess the front slows down less compared to the back in the second 50. That is why this should be done in percentage terms :)