ERG vs. Slope

Excited to hear in yesterday podcast that there will be the option to dynamically switch between ERG and Slope within the same workout and perform intervals in Slope.

I often do workouts at the gym (on the Stages bikes, equipped with power meter, but no ERG) and found that I tend to do much better when the trainer is not controlling tightly the power, especially the ones where I’m close to my limit.

Mentally, knowing that if you slow your cadence, resistance will increase, can be detrimental and cause abandoning a workout early.
The opposite is also true, and on a good day I may feel like pushing a bit more than prescribed.

So I was curious if any study has been done about the benefits/drawbacks of ERG mode vs the open loop (Slope/Resistance).
ERG is very “artificial” and obviously not representative of real world cycling, so I guess my question is if it is beneficial, neutral or actually sub optimal.

I’d be interested in this too.

I find that I often use ERG mode even when doing a virtual climb, as it does not require shifting gears, which is inevitable when not using ERG mode. This helps me focus and I can change cadence as I want, while the power target will not change.

As I’m using an app to control my trainer (Tacx app / Neo), it’s easy to adjust power, although in my case this is only possible in 5 Watt steps. But for me, that’s good enough.

However, this obviously doesn’t really work when doing workouts with (lots of (short)) intervals, as I will have to push the up (or down) button 20 times to increase power by 100 Watts - do the math on intervals with even higher differences…

So for those workouts, I will render control to the app, like Xert Player.

And whenever I want to do a ‘real life’ workout, I switch to ‘smart mode’, so resistance will change according to grades. I like this when doing virtual rides that are in undulating terrain.

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Quite a bit of stuff on this in the interwebs.

Long thread on this in SlowTwitch:

Some people hate it:

Is ERG mode killing your training?

I’ve seen that SUF post before - I would previously agree about ‘your trainer not knowing your FTP change’, but with Xert’s adaptive training - and no FTP testing - that isn’t really an issue (anymore)…

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I’ve read the [360 VELO] piece now as well - while the reasoning makes sense, it’s a bit too negative an explanation for me. Using ERG mode doesn’t make me dumb, I still vary (a lot), both in cadence and power and I always focus on the the transition between intervals.

I just see it as two different disciplines and having more options makes indoor cycling / training more interesting…

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After training for a years on ‘dumb’ trainers, I was excited to try ERG when we finally got a smart trainer. After a while the novelty wore off and I’ve switched to resistance/slope mode for the majority of my workouts as I find being able to switch gearing and cadence much better and find it also keeps me more engaged in the workout mentally rather than switching off and just peddling. Where I do think ERG is useful is during recovery intervals or workouts at lower intensities, I’ve tried just riding Zwift routes for endurance workouts but always end up riding harder than intended and a pure endurance workout usually ends up becoming tempo/sweetspot instead.

The option to perform intervals in resistance/slope mode and then recovery in erg sound perfect to me, must admit I was really pleased when Armando revealed this feature in the latest podcast as I am guilty of often riding too hard during recovery intervals.

I’m not sure if one format is better than the other, my wife likes ERG mode as in her words ‘it keeps me honest, because otherwise I’m lazy and cheat!’, I think mixing the two is probably the perfect scenario.

Great topic. I’m actually going back to a dumb trainer + power meter setup, and selling my Kickr. The novelty is gone. It might be different if I were into riding in a “game” app, but its all about interval training and outdoor riding for me. There is much to be said for controlling and sustaining your power output yourself, by gear, cadence, and feel - hard to express, but its more “riding-the-bike-like” action and feel to me. I think I’ll spend the $$$ I’d have spent on the next smart-trainer set up for a Haute Route trip or something.


That is what the new options let you do. Start a workout (defaults to ERG) then switch to resistance mode and use cadence and/or gearing to hit your targets.
With this new function I primarily use ERG for warm up/cool down minutes or rapid fire intervals of high intensity. In resistance mode you also see how Xert’s cadence optimizer logic works.


I use Erg mode all the time when I’m on my trainer. Contrary to what I’ve read, Erg has improved my pedalling smoothness and my ability to hold a constant effort on outside rides. It’s almost as if Erg has taught me what it feels like to pedal at a constant wattage. As I only do about 10% of my riding on a trainer I’m not really worried about getting so used to it that it adversely affects my outside riding. It’s also helped me greatly when following a wheel in a group ride which seems to very similar to Erg in that something else (the guy in front) is setting the pace (much like Erg) and if you loose concentration and start to drop your cadence you pay for it.


i agree , ERG has improved my cycling 10 fold , i’m significantly stronger as its like having a NAZI as a coach , its relentlessly asking for more effort or get off , simples


As always, it depends…
On longer steady state (like Sweet Spot or near threshold intervals I think ERG is great, but for short intervals like 1 minutes or VO2max 4x4 I like to have the option, when I feel good, to go harder if I can or hammer the end of the interval.

In the end ERG can force you to go harder but also limit when you can go harder.

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Yes, although I can ‘trick’ my Neo by just increasing RPM a lot instantly and it will take a few seconds to adapt and dial back the power to the set level. This only works if you surprise the thing - if you gradually increase RPM, this won’t work, obviously.