Patrick Lange ran a 2:39 this weekend after biking 112 miles and swimming 2.4mi to win the Ironman world title. All that in Kona weather, which the IM website describes as:
"Temperatures on race day range from 82 to 95 degrees Fahrenheit, with the humidity hovering around 90 percent. Crosswinds on portions of the bike course sometimes get as high as 60 mph."
How fast do you believe he could run a marathon with fresh legs, in good weather and on a good course like berlin, but not with this year's weather?