The Ironman Marathon
August 25th, 2009In an article on the Training Peaks blog, Matt Fitzgerald describes how to nail the Ironman marathon:
“Get as strong as you can on the bike.”
I always read what Matt has to say, ‘cos it makes a lot of sense. I think he may have missed something here though, and only given us part of the story. Like so many things, there are a lot more parts to the puzzle than just the statement above. Here’s one…
In my experience, Ironman athletes who get stronger on the bike don’t necessarily run any faster, they simply put in a better bike split.
For me, the true secret to running an Ironman marathon near your ability lies not in how strong you are on the bike, but rather in how well you pace the bike leg of your Ironman in relation to that strength.
The triathlon world is littered with athletes who are very proud of their 5-hour Ironman bike splits, but who have never run anywhere near the 3:05 or so marathon that you should expect from someone who rides that fast. After all, surely more bike fitness should equal a faster run?
What you actually need to do is to work out from your training:
1. How fast can you ride 112 miles?
2. How fast should you ride 112 miles in your race?
The first is easy. There are a number of more involved methods I would use for my athletes, but a simple way to do this is to go out & ride a 112 miles as fast as you can on a course with a similar profile to your race. Do this 6-8 weeks or so out from your race. You might get a bit faster, but in this volume phase of your training, this gain will likely be minimal.
The second gets a bit more complicated though. I’m still working on the details, but from my coaching experience, I’ve noticed that most of the better marathon times have come off a bike split around 5% slower than the athlete’s actual ability over 112 miles. But of course, there are a lot of variables here too, not least, how well trained the athlete is for running a marathon & therefore how well they hold their technique when they’re tired.
Of course, knowing how fast you should ride is only part of the picture. You also need to make sure that you’re well enough trained as a runner that you can hold good form throughout the marathon. And you need to work out how fast you should be able to run so that you pace yourself well. But that’s another blog post…











