The 25 page 'Ironman Athlete Guide' came out this week, detailing all the minutiae that go into the Ironman race. In that guide was an elevation profile for the bike course. Observe:
Just shy of 4,000 feet of climbing. For comparison, Mt. Everest is 30,000 feet. So, my course isn't totally killer - if you consider that 4,000 feet of climbing is spread out along 112 miles. The good news is that my legs are as strong as ever.
The bike course is a '2 Loop' bike course, so you ride up from sea level at the Hudson River, ride north through New Jersey and up into New York. Then back. Then do it again.
6+ hours later I will be ready to start a marathon - which usually when I start out for a marathon, that's the only thing I'll be doing that day.