Cycling For The Ironman

What does it take to improve bike performance for an Ironman race?

Thanks for the question Tea. Here's my attempt at explaining my current philosophy in regard to the cycling portion of the Ironman triathlon.

My Background

Having attempted a mixture of so-called old school and scientific training over the years on the bike I have found a simple approach works best for me. Initially I just went out riding with different people over different terrain, and before I had any of my studies under my belt, I aimed to replicate the demands of racing in training. Later, after I had a bit of research, a degree and other knowledge under my belt I decided to take a more directed, scientific approach to my cycling. I imposed cadence guidelines, very specific heart rate zones and interval times. With hindsight, I found I raced better following the old school approach, but to get the best out my training some direction is needed.

Demands Of The Event

Different courses require some different elements of fitness and skills. For example the pure flat roads at Ironman Western Australia present a very different challenge when compared to the hills and more technical Ironman Australia in Port Macquarie. However, the distance to be covered is still 180km, preceded by a 3.8km swim and followed by 42.2km run. Therefore, the core requirements are still the same.

The bike leg will take most people somewhere between 4.5 to 7 hours. Most will perform the race at an intensity of 55-75%VO2max or 60-80%HRmax. This is not fast. It is a low intensity when compared to other shorter events. In fact, many people will ride harder in a good number of their own training rides. Yes you can ride portions of the bike leg faster, but this is likely to result in very poor run performances. It is important to finish the bike leg with enough in the tank for the run. To achieve this there are three key elements that need to be developed for the bike.
  1. Aerobic conditioning the allows efficient use of fuels
  2. Local muscular strength and endurance to sustain a good power output
  3. Core conditioning to be able to remain comfortable in race position for the event


Essentially this has been covered to some degree in my previous posts:

It All About Fat and Sugar

Training and Fat - Part 1

Training and Fat - Part 2

To reiterate, the basic goal of the majority of training is the develop the body's aerobic abilities to enhance the use of fat as a fuel, limit usage of stored glycogen and to efficiently use ingested carbohydrate. In short this is achieved through prolonged (2-6+ hours) training sessions at 60-80%HRmax.


It doesn't matter how good the heart and lungs are if the legs can't take you the whole distance. Yes you can improve your aerobic conditioning with swimming and running, but if you haven't put time into your legs on the bike, chances are they will give out before 180km is up.

Over the last few years there has been a popular trend to focus on high cadence cycling. The success of Lance Armstrong has certainly improved the popularity of spinning the legs at faster rpms. However, I believe the approach for most people has been a bit too extreme. Cadences over 100rpm at low to moderate intensities does play a significant role in helping improve central aerobic conditioning, plus, paradoxically developing the slow twitch muscle fibres. For myself, and a number of other triathletes I am familiar with, I have found that focusing too much on high cadence work can lead to a reduced ability to generate appropriate force or wattage in time trial or climbing situations. With that said, it is also important to move up from purely mashing big gears at low cadences like 60-70rpm.

What works for me? In terms of cadence I generally let things fall into what feels comfortable with a small percentage of work at the outer areas of what feels comfortable. It is hard to much more specific than this because my comfortable cadence range varies of terrain, time and intensity.

For developing muscular strength and endurance I find mixing a regular long ride at 60-80%HRmax is important. It is important to maintain a steady effort throughout, aiming to minimise freewheeling and those times when you fall into the trap of soft pedalling through boredom. Physically these rides aren't too hard, but it does require a strong mental effort towards the end just to maintain proper form. Mixed into the week and depending on the phase of training I will include sustained harder efforts. Many interval sessions are performed on the turbo-trainer.


It is important to be able to remain comfortable on the bike for the duration of the ride. Once a good fit on the bike has been established there is an element of conditioning that goes into being comfortable for the 180km journey.

Reasonable flexibility is required in the posterior chain. That is, hamstrings, hips, glutes, lower back, shoulders and neck all need a good functional range of motion so as not to place undue strain in any body area. Therefore, regular flexibility training is required. For me this includes daily static stretching post training sessions, dynamic range of motion exercises in warm-ups and attention to position withing the training session.

Core strength work is important to create a body strong enough of remaining in the race position and still generate a good power output. Basically you need a solid platform for the legs to work from to spin the cranks round and round. I achieve this through regular work in the gym, using many compound, multi-joint exercises, plus specific core strength exercises.

Familiarity with your race position(s) is important. Don't make race day the first time you attempt to remain in the aero-position for over 5 hours. Practice this in training. Race day is about doing what is most efficient for your body to achieve your best time. If you're not used to be being down on the aero bars, you will fatigue in body areas that are not well conditioned. Practice in training, what will be expected on race day.


Above all I think the most important elements to improving cycling for the Ironman is simply time and consistency. Get out there and put in regular training day in, day out. Put in some regular long rides and have give yourself enough time to allow the body to adapt and see real improvements.


  1. That's a great post! Thank you so much! I have to tell you that I don't have anywhere near the expertise or knowledge that you have. But I played around with my diet prior to my HIM (based on your previous posts), and I felt the best that I've ever felt during a race.

    The second issue is cadence. I'm so glad that you said that. I feel really good at a lower cadence (80) on my long rides. So maybe I'm not crazy?

    thanks again.

  2. Good post! Lots of useful information in there.

    Getting used to be in the aero position for hours on end continues to be a pain point for me, but will be a HUGE part of this winters training plan.

  3. Great post, your blog has so much good information!

    I'm always interested in the cadence question - there seems to be such a variety out there on the race course, but I always wonder how the different folks fare on the run.


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