What’s the best bike cadence for Ironman?
When racing Ironman, what’s best – high or low cadence? Joe Friel prescribes your peak rpm
There’s a race in the United States called Race Across America (RAAM). The field is small but the athletes are serious. It takes the solo riders a week or more to bike from the west coast to the east coast, riding 200 to 300 miles a day. They pedal with a very low cadence – around 50 to 60 revolutions per minute (rpm). But when facing shorter races, these same athletes pedal with a higher cadence.
It’s something I’ve noticed with my own athletes. When racing a sprint they were around 95 to 100rpm, but when they did an Ironman they pedalled at about 80 to 85rpm. When asked about this they were unaware of it happening.
Since this discovery I’ve come to understand why good athletes doing long, slow distance events typically pedal at low cadences. If you understand, it may help your bike performance on race day.
To my knowledge there has been no research undertaken on the relationship between cadence and race distance. But there is research on something called ‘efficiency’. And it may help us to comprehend this pedalling mystery. But before that, let’s look at what it takes to race fast…
When it comes down to it, there are only three physiological fitness improvements you can make as a result of training to ride faster on the bike. The first is to improve your aerobic capacity. Also known as VO2max, this is the one most coveted by the average triathlete. It’s a measure of how much oxygen it takes to produce a maximally high power output for several minutes. Every endurance athlete wants to find out that they have a high VO2max when tested. But is this really necessary for success in an Ironman? I’ll come back to that question shortly.
The second improvement triathletes want as a result of training is raising their lactate threshold, also known as the anaerobic threshold. This is the intensity level at which you begin to ‘redline’, meaning several things: lactic acid is beginning to accumulate in the bloodstream; you start to experience a burning sensation in the working muscles; and fatigue is becoming obvious. You might be able to last for about an hour at this level of intensity. Lactate threshold is expressed as a percentage of VO2max. Fast, short-course triathletes generally have a lactate threshold that occurs at about 85% of VO2max. Mere mortals, like the rest of us, are more likely to be in the range of 75-80%.
The last physiological improvement you can make to go faster is to become more efficient. This has to do with how much energy you expend to produce a given sub-maximal power output on your bike. Just as with your car’s fuel (petrol) consumption, as a long-course triathlete you want your body to use fuel (carbohydrate) sparingly. The rate at which you use energy is critical to success in long-course racing.
So why am I telling you this and what has it got to do with your cadence in an Ironman bike? Good question. Here’s what we know. The shorter your race is, the more important VO2max becomes to the outcome. The longer the race distance, the more important efficiency is to the outcome. Lactate threshold fits nicely some place in the middle as a determiner of race times in triathlons at about Olympic distance.
So with that knowledge, let’s get back to pedalling your bike.
All About Efficiency
If efficiency is the most important aspect of physiology in doing an Ironman triathlon, a logical question is: “What is the most efficient cadence when pedaling a bike?” And you guessed it – low cadences are more efficient than high cadences.
Much research has shown that even with experienced cyclists, the study subjects are more efficient
(use less energy to produce a given sub-max power output) at low cadences than at high. But when VO2max or lactate threshold become the key determiners of race performance at shorter distances, higher cadences are
So what does all of this mean for your training? If you’re preparing to race an Ironman, you should pedal with a lower cadence than if training for a sprint. Cadences in the low 80s seem to be about right for long-course. Cadences in the high 90s seem to work best for sprints. For the Olympic- and half-Ironman-distances, cadence will fall between these extremes.
The triathletes I coach develop a broad range of cadences they can pedal at comfortably. That means spending training time at 80, 90 and even 100rpm throughout the Base period. But as they begin to train specifically for the Ironman distance, especially in the last 12 weeks before the race, their cadences shift toward the low end of their comfort ranges. This will optimise their efficiency and produce a fast race – something you must bear in mind for your big race.
Improve your pedalling
The best drill for becoming a more efficient cyclist is to pedal at a very high cadence. This drill may be done on an indoor trainer, rollers or on the road.
On an otherwise easy ride, every 5mins or so for 15 to 30mins, increase your cadence slowly over a 30sec span until you’re turning the cranks at your top end. You’ll know when you get there because you’ll tense up and start to bounce on the saddle.
Practise staying relaxed when you reach this high cadence and your body will learn to pedal more efficiently – if you do the drill often enough.
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