Decreasing cadence in workouts

So I have noticed an effect on my cadence over the course of workouts, some I start out at my usual cadence of 87-92 but as the workout continues, my cadence decreases. In other workouts at a certain resistance my cadence is crushed immediately and sort of stays crushed, so I am muscling through the intervals, where I would prefer to “spin to win” at a cadence around 90 instead of 75. I am using Erg mode on a Saris H3.

I guess I am just looking to understand these cadence changes better, in Z2 workouts, does a declining cadence mean I am reaching my endurance limits? In Z3 and up workouts I guess its just the amount of resistance is decreasing my cadence.

I have included a few examples but I know its hard to perceive the change in cadence by looking at the lines.

In Dombai, in Endurance interval 4 (avg power 148), 12 mins from 26 mins to 38 mins my average cadence was 89, by endurance interval 12 (avg 148) 12 mins from 1:24 to 1:38 my average cadence was 80.

Does this tell me anything in terms of optimizing my Z2 work? Should I look to complete Z2 workouts where I can maintain my cadence throughout the workout?

In Hogback, I felt the intervals immediately crushed my cadence, perhaps this was intended, I would have preferred to maintain a higher cadence but instead felt like I was trying to muscle up a long climb in the big ring (which I used to do but now feel that it leads to muscular fatigue for me, leaving me in a noodle leg state).

Is there anything I can take away from this? In my outdoor riding, although I don’t ride with a cadence sensor I would try to avoid letting my cadence slow to that grinding cadence as I find it very fatiguing but it seemed like I couldn’t do anything to prevent it during that workout.

What gearing are you using while in ERG mode?

Broadly speaking, what I see here is you either fatiguing over time (pretty natural and part of the training process) and simply not holding your cadence as is basically required for general ERG use.

The slow decay in the Z2 workouts shows you are fatiguing and just not able to spin faster. Could be muscular and even aerobic to a degree related to HR.

The quicker drop in the harder zones is just you not “answering” the demand of the increased resistance. Holding whatever cadence you desire is key for ERG, and almost entirely up to you. It’s why I say “Cadence is king” for ERG mode, and that cadence is up to you to control.

Getting tired does happen and I have some cadence decay that happens most often at the end of intervals, especially ones at or towards the end of the workout. At times we can muscle up and “get on top” of the cadence again, while others we are simply cooked and can’t hit that cadence

This is one reason people sometimes prefer non-ERG modes. But they are subject to the same fatigue and I would expect that they are either shifting to different gears if they are able to maintain power, or they are dropping below the power target in the same or different gear. None of these trainer modes are devoid of issues related to power targets and cadence. Just different ways to hit power targets.

Could be worth testing other modes if you have that interest. But do keep in mind that swapping modes also leads to different gearing in many cases, so any “change” you feel needs to consider gearing in addition to the mode difference and how it feels.

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I concur with @mcneese.chad - I often see my cadence decrease over time just due to fatigue. If it’s a minor decrease, and I am able to meet the power target, I don’t think it’s anything to be concerned about. I either try to slowly increase cadence back to the original cadence, or at least prevent it from dropping further.

What’s bad in ERG mode is if your cadence gets so slow that the resistance on the trainer gets bogged down and you can barely turn the pedals! So when the power kicks up in ERG mode, definitely be prepared to monitor and keep your cadence up.

Also, the concept of “spin to win” that we hear so often has been put to the test in studies, and the current conclusion is that your favorite self-selected cadence is more often than not the best cadence for you in the moment. See Is There an Optimal Cycling Cadence? The Science - YouTube and maybe this was covered on the TR podcast too at one point.

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Up until probably a month ago I was using 53 and the middle of a 12-28 cassette ~19, I am now using 39 and ~19. I had previously complained about difficulty hitting 15-30 second intervals, as it seemed to take 5-10 seconds to hit or exceed the target power. At that time you had questioned my gearing and suggested using the small ring but I was hesitant to do so as I couldn’t calibrate (spin up to 40 km/h) without using the big ring, I can now calibrate with the small ring so have been using the small ring (39T).

In terms of “not answering” does that mean it is hitting a weakness or something? I did successfully complete the workout but didn’t like how it bogged me down, I am recovering from the flu and know in the past (August) when I failed workouts for the first time it was shortly before I tested positive for covid so maybe my fitness is a bit down right now?

Looking at similar workouts, I was able to ‘answer the call’ with Holt Hill -1 on Dec 21st with Tempo interval 1 with an avg power of 174, I averaged a cadence of 91. with Deerhorn -5 on Nov 6th on Sweet Spot interval 13, I averaged a cadence of 102, Glassy -1 on Dec 27th I averaged a cadence of 95.

However, maybe more indicative of some sort of physiological weakness, I see with Pioneer -1 on Dec 31st my avg cadence was down to 80, Tempo interval 10 (avg power 180) my cadence was 72.

Would this indicate a weird weak spot in my fitness, that Pioneer -1 and Hogback are exposing that other threshold, sweet spot or tempo workouts aren’t really exposing?

Like Julie K said, I wouldn’t worry about it, your natural cadence is your natural cadence. Your brain and/or body can get tired and slow your cadence. Its natural. You can train for higher cadences but your body may prefer a lower cadence as it could be more economical (use less oxygen).

If you don’t like what’s happening in Erg on your H3, try switching from Erg to resistance mode. Or do a TR “outside workout” in Zwift in sim mode on a flat course. If you don’t like those options, go back to Erg.

  • OK, you need to separate things that don’t affect each other
  1. Spindown Calibration: This can be done in ANY gear you want. All that matters is getting the “rear wheel” up to the required speed, then costing and letting the trainer app determine how to adjust the power curve as a result of the spindown time.

  2. Actual ERG workout use: Gearing can be done in any gear you want, but should be considered with respect to your needs outside, as well as any trainer limitations. The latter part (trainer limitations) is one key reason that may drive a gearing choice. Nearly all trainer respond and handle resistance control better with slower “rear wheel” speeds. Hence the suggestion related to your issues with response time. But like anything in life, you have options and balancing the goals and desires you have is likely necessary. Meaning that just because one gear solves one problem, doesn’t make it the right one for all uses.

Related to any gearing change for ERG use, it can be useful to test in the same/similar gear that you plan to use for your workouts. For instance, if you had previously tested in the 53t and trained that way, then just swapped to the 39t, it can alter how you feel and respond to workouts in that lower “rear wheel” flywheel speed. I am pretty sure I also recommended a new FTP test if you made such a large change in gearing. Up or down that much will most likely have at least some impact on the “FTP” and how you respond to workouts with notably different flywheel speeds.

If you go into a workout and aim to hold 90rpm, but end up sliding down into the 80’s, that is what I mean by not “answering” the effort. The actual wattage level is set by ERG and the app, so you are responsible for applying your power at the cadence you desire. Cadence lower than that is likely do to:

  • Inattention where it changes because you aren’t paying attention but still have the ability to hit it if you watched it.
  • Or from fatigue as your muscles and/or aerobic system are unable to hold that cadence over time at the given power level.
  • That is important to recognize and at least partly answers your own question as to the cause of the cadence decay.
  • That’s where we go above my pay grade :wink: I am no expert when it comes to the more specific nature of our performance in workouts and how to address them.

As others covered, there is not necessarily a magic cadence. But I do think that it is useful to train at cadence ranges that make sense for your needs. I’ve seen comments from people that say they train inside at cadences notably different from what they do outside. Could be marginal gains territory, but a difference like that seems like a mistake to me and an opportunity to improve the “specificity” of the training to more closely mimic your goals and needs.

I guess I am asking 2 separate questions;
Does cadence decay in Z2 mean I should decrease or maintain at that IF rather than advance? For example, a recent PR for me was completing my first Z2 3 hour workout (Broken Hand) I was supposed to do Walker but felt too sick to handle the higher intensity so did that instead (TR rescheduled Walker for me to do this week and will give it a shot tomorrow). As I noticed my cadence decline over the course of Broken Hand would that indicate I should do Halifax (a lower IF Z2 3 hour workout) instead or stick with Broken Hand for a while rather than moving up to a higher IF Z2 workout like Inscription Rock?

The other question is, what does it mean that Pioneer -1 and Hogback seemed to crush my cadence when other Tempo, Sweet Spot and Threshold workouts have not. Maybe this will resolve, when I am fully recovered from the flu but if not, I have no idea what that would indicate, if the intervals of those workouts cause a ~20 rpm cadence drop while other, similar workouts do not.

I see what you are saying about the calibration, was unsure about that in the past so felt I had to calibrate in the gearing I used but understand what you are saying, I don’t think my FTP has increased (according to AI FTP) since the summer when I was unable to spin the trainer up to 40 km/h in the small ring for calibration but it seems I can now, ‘so I’ve got that going for me, which is nice…’

Your follow-up questions fall well into that Training side I mentioned, so I will leave those to others to answer. I have no confidence in helping people with that type of info.

Regarding getting “bogged down” in the higher wattage intervals such as Tempo/SS/etc… in my experience, I find that as the workout progresses and I know I’m getting some fatiguebuilt up in the legs, it’s best to make sure you “stay on top” of the upcoming power increase BEFORE the increase actually happens…

I would usually handle this by increasing my usual or DEFAULT cadence by 5-10 rpm about 10-15 secs before the interval starts. The trick is to make sure to increase the cadence GRADUALLY so that the trainer doesn’t freak out trying to adjust for what could be a substantial power uptick when you tack on that 5-10 rpm all at once. Usually then I find that when the interval starts and the power ramps up, if I my cadence slows, it doesn’t go much below my usual cadence (if at all).


Power = force x cadence

If your cadence drops then you need to put more force through each pedal stroke to achieve the same power. More force means recruiting more muscle fibres to fire as you apply it.

I’m a relatively high cadence cyclist, around 80-90 rpm is my self selected and sometimes higher. I found if my cadence dropped and the power requirements were high then I’d struggle to generate enough force.

I’ve started doing what are called strength endurance workouts. These are low cadence (40-60 rpm) intervals of around 10 minutes at a high percentage of my FTP (85-95%). I do these outdoors on shallow hills as my trainer doesn’t like such low cadence. These really help where I have no choice but a lower cadence and have improved my force production. Make sure your knees are good if doing these and keep at top of that cadence range initially.

Combine the improved force production with my natural cadence and my power output goes up as a result.

After all going fast is about turning a big gear at a high cadence.

Can’t really comment with anything scientific but I now do my training in the small ring. Purely because my bike is trainer specific and it’s cheaper to replace the inner ring :slight_smile:
I think the feel of the workouts is different also due to a change in flywheel speed, it feels a little harder as there’s no ‘help’ from the trainer.

agree with this. Perhaps you aren’t getting on top of those harder intervals.

Over the course of the past couple of years, my preferred cadence seems to have dropped from 80-85 or so to more like 75-80. On the trainer I tend to be on the lower end of that even during threshold work, and a bit higher on a real bike. Somehow my scrawny ass has become a grinder. Not sure what to make of it.

Wait a minute - I think the fact that you are still recovering from the flu is a huge variable in your findings! Right now my guess would be that all of this data is tainted because your is body recovering from the flu, hence added fatigue in the legs and things feeling harder than they ought.

A 3 hour Z2 workout is not a flu-recovery ride! It’s hard, actually. I’m concerned - please take care of yourself and take some added recovery days, or at most do a Lazy Mountain 1 hour until you’re fully well!

My natural cadence is 80-85rpm, and over the years I’ve always done low-cadence work (overgeared at 55-65rpm) at endurance and low-to-mid tempo (appears to improve performance).

I’m routinely doing multiple 2+ hour endurance rides every week, under a coach. He has never advised changing the power target of an upcoming endurance workout because he noticed decreasing cadence.

However when my coach notices my cadence on those 2 hour endurance rides consistently dropping to mid to upper 70s, he will give me an undergeared workout of

  • 5-minutes at low zone3 (tempo) power and 105rpm target
  • followed by 5-min low zone2 at 85rpm

And repeated for several sets.

The point of the workout is to rebuild leg speed and smoothness. The key here is to only spin as fast as you can smoothly pedal - never reinforce bad pedaling habits.

Now if I can only spin smoothly at 95rpm, then thats what I’ll do (never reinforce poor pedaling). And I’ll continue working on leg speed during warmups and endurance rides. Eventually, over the course of several weeks, I’ll rebuild my leg speed to doing 2 hours of endurance at 85-90rpm. And that is usually timed before fast group rides, where having a wide usable cadence range is important for covering moves.

I’m not sure if I followed all of that, as you had some 90+ rpm tempo intervals in November and December. Sounds like something that happened very recently and is not a consistent pattern.

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