What's up Sage, just ran my first road marathon, and I surely learned first hand what the marathon bonk is all about. Up to 17 miles, my efficiency and overall effort was solid, all I could muster the last 9 miles or so was a shuffle for a minute or 2 max before my quads and calves began cramping badly. I did finish, but ended up pretty dehydrated from the humidity. The course was brutal, just shy of 2,000 ft of climbing, for a road marathon, I'd imagine that's up there as one of the tougher course profiles. With all that being said, did you find the transition to trail 50k to be "easier" on the body than a road marathon? I've raced half dozen road halfs and a road 30k, the marathon for a first timer was just another world, and I am an experienced runner. I definetly want to run another marathon next year, but the trails just seem more enticing past the HM distance, 26.2 miles on pavement is TOUGH.