Hi, I’m doing the IM Level 2 plan with bike power and run heart rate. All intervals are specified as time. As I near the peak of the plan I notice the longest bike is 6 hours and run 2:45. At my FTP of 209 and w/kg of about 2.9 my IM pace for a hilly bike will be about 6:30. Should the 1-2 long ides be 180 km+ or about about 165-170km that I can cover in six hrs? Ditto for the run at 2:45 and my 6 min km pace I’ll be well short of a typical peak long run of 32km or so. Should I run at least 30-32 km and ride 180? Thx
I think this is best answered by quoting…me. From Chapter 6 of the book 80/20 Triathlon.
One unresolved question you may have about time-based training is this: “Since my race requires that I complete a certain distance, not a certain time, don’t I need to cover the approximate distance of each leg of my event at least once in training?” This question is particularly applicable to Ironman training because it is easy to meet or exceed the swim, bike, and run distances of sprint, Olympic, and even half Ironman triathlons in workouts. The short answer is no. It is not necessary to complete a full 112 miles of cycling in any single bike ride or 26.2 miles in any single run before your Ironman event. The full answer is
that, when you’re training for an Ironman, it would be wise to cover at least 100 miles in a bike ride and at least 20 miles in a separate run workout. These infrequent, outlier workouts can still be scheduled based on time, however, using your estimated average speed or pace to convert distance to time. For example, if your Zone 2 average cycling speed is 17 mph, you should plan a 5-hour and 45-minute ride if you want to cover 100 miles.
Page 70-72 covers more reasoning on using Duration instead of Distance.