About fifty percent of your Ironman will be spent on the bike. How you pace yourself will not only impact on how quickly you get round the bike course, but also how well you run the marathon.
Ironman performance is restricted not only by fuel but also by fitness. The more industriously we practice the faster we use our valuable but limited glycogen stores. When they are exhausted, we get that horrible feeling of hitting the wall. The answer is to ride at an average intensity, which enables the body to make use of more fat as fuel and save on glycogen for the run. Here’s how:
Power
Although a power meter is costly, it is the greatest way to ensure your effort levels are accurate and even. Once you have figured out your best power output for the Ironman distance you ride as near to the number as possible. If you divide the distance in half, a first-rank power profile would mean that each half was within about 5 percent of the other.
You should allow your power output to drift about 5 percent when riding up hills and you can let the power drop by 5 percent when descending. This is because the power required to overcome aerodynamic drag rises with speed.
Heart Rate
If you have figured out your heart-rate training zones on the bike, you should ride the whole distance in zone 2. Don’t make the mistake of using heart-rate zones derived from running, because they usually will be 8-10bpm higher. Besides, it is better to target a heart-rate range than a particular number, because of variables such as tiredness, heat, aquation, solicitude and morpheus.
You will also find that heart rate drifts higher for the same effort over the course of an Ironman because of cardiac drift – the result of increased tiredness and decreased aquation.
Speed
Maintaining a particular speed for the duration of the bike leg is a indeterminate way of pace judgment because of external factors such as gradient and wind. However, over a flat course such as Ironman Florida or Melbourne on a windless day, it can be used in conjunction with other ways of pacing.
Feel
Feel also can be called perceived exertion; it has been shown in research to associate well with other measures such as a heart rate, power and lactate. On a scale of 1-10 where one is resting on the sofa and 10 is the point of maximal effort, the first half of the Ironman bike leg should feel like a three and the second half like a four.
But the problem is that feel is very subjective. A bridle-wise sportsman is likely to feel good on the bike for the first few hours, so runs the risk of pushing too hard. In Ironman that means trouble on the run. As an isolated way of pacing, perceived exertion is deficient but not unnecessary.
Triangulation
If you do not have a power meter you can target a heart-rate range and a rough mean rolling speed. Knowing how those feel in the first half versus the second half of an Ironman bike distance, you can figure out how to pace your race. The key point rests with doing your homework. Have you researched the route? Considered the changes in gradient? Looked at typical wind speeds? Done the distance in training? Have you tried running off 180km? Pacing is an acquired skill and, like all skills, it’s improved by homework and hard work.
Make it work for you: Rolling loop race practice
If you’d like to keep things simple on your Ironman bike leg – or are new to tri and need a trick that will work in shorter races – learn to pace by feel with a rolling, twisty training loop that’s just a couple of miles long. All you need is a watch to learn to pace your laps evenly and experiment with how hard you can push yourself over different numbers of laps, up the gradients, and round corners. It’s good practice for multi-loop short races, too.
