One of the FAQs that regularly pops up in bike sessions is about Cadence – how fast should you pedal, is there a ‘right’ speed and so on. Well, it depends…. For triathletes, a critical additional factor is that you have to run when you get off the bike, so that riding cadence isn’t just related to your cycling performance. One of the arguments in favour of lower-cadence riding is that it’s more efficient, ie your heart rate (HR) is lower,so you’re generating your target Wattage at a lower ‘cost’ to your body. That’s true actually, and in real-world terms you’ll often see a Strength Set in a turbo session where you’re asked to ride at eg 60rpm and 75%FTP so that your heart rate stays low. Most riders will have their ‘preferred cadence’, where they feel pretty comfortable, and that’s usually where the discussion starts. That may be quite different from their most efficient cadence – where they can deliver the power required (% of FTP) for their race duration at the lowest physiological cost. FTP is your Functional Threshold Power, the power output (in Watts) that can, notionally, be sustained for 60 minutes. That’s the anchor point for Power: long-distance triathletes looking at a 5-hour ride might have 75%-80%FTP in mind for their event, but a Sprint-distance triathlete will likely be thinking in terms of 105%-110% FTP, or maybe a little higher. So their heart rates will also be operating in a different range, and of course they’ll have trained at their target intensities. Coaches will often have a default recommendation of 90rpm – and that’s fine, as a default setting; but as with other elements of training it is often a starting point around which the athlete can experiment. 90rpm does suit some riders perfectly – but for others, it’s not going to be right. So, what other considerations will be (or should be) part of the Cadence discussion?
For me, cadence ‘range’ is important, and under-rated. Whatever number is finally settled on – for whatever reason – having a range of, say, +/-10rpm around that number where the rider is still comfortable and efficient is really important. It’s unlikely that a rider will be able to sustain [for example] 85rpm consistently throughout a race – the wind and gradient will be variable, and drive the rider to be faster/slower than their target 85rpm, or they need to change gears but their closest sprocket is sufficiently different that the cadence is significantly affected. So moving to a harder gear and having to ride at 80rpm to maintain Power, or moving to an easier gear and having to ride at 90rpm may be a huge challenge for some riders. Part of the solution then, regardless of where your target cadence lies, is developing some ‘range’ so that you can manage those small variations. Winter turbo is a good place to start developing that range. Try a ‘Cadence-Fartlek’ session where you ride at a consistent output for 45min – let’s say 90%FTP – but switch your gear/cadence combination at every 5min point with quite big changes. Afterwards look at how your HR has been affected. Start to condition yourself to operate at a range of cadences: try an interval session where you keep the Power consistent at different cadences. For example, 3x[ 3x 3min @ 110%FTP @ 85/95/105rpm with 2min recoveries] but using 3 different gears within each set. That would be your preferred gear/cadence for this kind of effort, alternating with 1 gear harder and 1 gear easier – your Power output will be the same throughout, so you’ll definitely be working hard, but you will be operating at 3 different cadences. Again, look at your HR numbers after the session – even within a session like this there will be some acclimatisation; and if you repeat it (or similarly constructed sessions) you’ll see more acclimatisation.
Like I said earlier, it’s true that lower cadence with higher resistance generates a lower HR, so has a lesser physiological cost. But in a race there’s always something else going on. Imagine a draft-legal Sprint distance triathlon where you need to be instantly responsive to other riders in order to stay with the leading group. Or imagine a long-distance triathlon where a series of on-coming trucks generates sudden blasts of wind against you: if you’re mashing a too-big gear and admiring your low HR, it will take a minute to get back on track to race pace. Or maybe you’re on a course with lots of roundabouts: yes, you may have changed down a couple of sprockets on the approach, but getting back up to race pace can take quite a long time. Then look for a moment at the Hour Record riders. This is the ‘Hour of Power’ on the track, where the record holders are almost all legendary riders – Coppi, Anquetil, Merckx, along with Chris Boardman and Graeme Obree. Within this very exclusive group of riders it’s actually Obree who stands out in relation to cadence – almost all of them set their records while turning the pedals in a very narrow 100-105rpm range. Obree, in contrast did 93rpm – in the context of this conversation that may be still pretty darned quick, but in the world of the Hour Record, it’s noticeably slow. Which points again to the need to look at the demands of your particular race, work to building a cadence-range where you can work efficiently, and actively practise some of your benchmark sessions at very different cadences, at your target output. That will prepare you for choosing the appropriate cadence for any situation. It’s not unlike a swimmer choosing their kick pattern to suit the needs of the moment in their race – just watch a swimmer like Katie Ledecky in a 400m, moving smoothly from 2-beat to 4-beat to 6-beat as the race progresses with the almost-inevitable outcome!
