Tom Danielson and Erg Mode

What about the adaptations which take place from variable/sawtooth “dumb” power, i.e. having to “lift” from 344 to 350…350 to 354…etc. Yes there are micro-breaks but also micro-boosts(?). Would also be interesting to know if those same breaks & boosts are also happening in ERG mode but aren’t recorded because ERG is holding power steady. Perhaps they are more similar than different. I certainly don’t know, and at the level of 99% of TR users, that marginal gain most likely doesn’t matter.


This mostly sounds like gibberish to me. I’m training for physiological adaptations, unless someone can show me how Erg mode doesn’t result in these physiological adaptations I’ll keep using it.


Ditto for dumb.

Unless someone can show me how ERG produces far superior physical adaptations…

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In my experience ERG mode is harder than having my trainer set to a set resistance level and using my gears. I am not sure if this is due to the timing/frequency that is sampled and gets processed by the trainer or what. I just find that I am forced to apply a more steady (not saying that I am making more power overall) power delivery throughout the entire pedal stroke in ERG mode. Where as when I am using a set resistance I can get to my self selected cadence and deliver the same power in a way that I perceive to be easier and feels closer to my outdoor pedal stroke (unweighted upstroke).
My bro science meter tells me that there a lot of techniques that are forced upon us by using ERG mode during the small amount of time that most of us ride indoors. If there is real training benefits to doing low cadence, one legged and other pedal stroke drills than I am getting it every time I use ERG mode. Just another non scientific reply to a sport where the strongest person rarely wins.


Here’s where the argument falls down, because at no point in a “real world” situation (ride or race) are you ever trying to hold a single power over varied terrain. You’re just trying to keep up or to drop your rivals. Look at any power file from a road race.

The only time you’re deliberately holding steady power outdoors is a TT or a long climb - and the terrain at that point is extremely _un_varied.

Apples and oranges, basically. As someone said above, erg mode intervals are a fitness tool, not a skills tool.


Oh hey, guess what?

When Tom D does his steady power non-erg intervals on Zwift, they’re all going uphill for the entire interval.

Except one where he goes over the top, and guess what again? The power gets a little erratic.

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How do you know? :man_shrugging:

I share this same experience - if my pedal technique starts to get choppy, the power will fluctuate a lot more when in erg mode and I end up needing to increase my cadence to keep more consistent power (and to give time for the trainer to adjust). The result is noticeably bouncy/ugly form.

Erg mode makes me focus on fluid pedal strokes which allow me to keep my desired cadence and minimize power fluctuation.

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I can also focus on fluid pedal strokes which allow me to keep my desired cadence and minimize power fluctuation on a dumb trainer.

I’m not a cheerleader/hater for either/or, I just think the perceived benefits of either/or might not be as great as the marketing implies, especially for riders who still have a lot of low hanging fruit to harvest.

The main benefit that keeps me coming back is that I don’t have to look at the screen the whole time, I can watch Netflix instead.


Via biofeedback, if someone smacked you in the face you wouldn’t need a dolorimeter or a MRI to be able to tell me it hurt. The human sense of touch is sensitive enough to feel the difference between surfaces that differ by just a single layer of molecules built over 200,000 years of evolution. That’s how I know…

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I’ve just got a smart trainer. I’m finding that erg locks me into a cadence band and forces me to ride smoothly at that cadence, the dumb trainer was a lot more forgiving of different cadences, and allowed me to switch between 85 rpm and 95 rpm during my intervals. I don’t know which is better TBH, the latter means I can use different balance of leg and lung power, but the former forces me to develop my lung power more efficiently.
Also, erg can allow relatively small steps or ramps. Have you ever tried riding Fang Mountain on a dumb trainer? You either have to bounce around your gears looking for one you can ride at the bottom and one you can ride at the top, or you have to try to ramp your cadence in a smooth manner. I just can’t do that. It also helps with riding an accurate ramp test - as I get closer to failure the difference between gears might mean a 30W jump in power. That would mean I would fail too soon because I can’t manage that gap with cadence while near my limits.
I’m planning on riding my fixie on the smart trainer - that’s something I definitely can’t do with a dumb trainer!


I’ve had 15 years on a Fluid trainer and a week on a Kickr Core using erg. I think the best answer is that you can (and maybe should) train with both effectively. Erg is good because it lowers cognitive load and is an unrelenting task master. I think erg is best suited for long intervals, say threshold and below, or long slow riding on the trainer. Check out, watch your movie or game, get the work in at self-selected cadence.

Thing about erg, is you don’t want to totally check out every time. Power should feed RPE, which then translates to the road when self-selecting power. You shouldn’t stare at your power meter when riding, instead aiming for a certain RPE appropriate to the effort required. Power feeds that. Erg can supply that training value as long as you’re paying attention often enough; in fact, it might do it better since you’re not thinking about your cadence or sticking target power and can instead focus on the feeling.

I think maybe VO2max level intervals are where the crossover starts to happen. I’ve done some 1-minute intervals at VO2 in erg, and many Vo2 workouts on the Fluid trainer. Erg allows you to get that cadence at 105 or whereever and stick it there; Fluid forces a certain cadence (usually 101-103 for me) to maintain target power. I could make a case for both.

Above VO2 or in those shorter intervals, I think resistance mode or fluid trainer is obviously the better way to go.

In all those years on the Fluid, I’ve gotten pretty good at maintaining target power, usually within +/- 5% (10W or so) either side, and usually closer than that. On the fluid trainer, I have a tendency to come in above target power on my intervals. In erg mode, I’m at target power for longer intervals, or under it some for intervals lasting about a minute. So Tom has a point about maintaining power. That said, I don’t think erg mode makes it impossible for someone to do it. I just think using both modes periodically and for certain rides will probably give the best results for most riders.

TL;DR: there’s a place for both, and there’s no absolute answer here, IMO.


Compromise and balance don’t sell books!!! :wink:

Absolutes and crashing the system… anarchy rules the news cycle!!! :stuck_out_tongue:


I feel like there’s some people missing the point here.

The purpose of interval training isn’t to exactly simulate real life racing. The goal is to ride in specified physiological zones for set amounts of time so that desired adaptations will take place during recovery. None of my race files ever look like my workout files, but that doesn’t make interval training useless.

If ERG mode helps you to hit those zones during workouts better, then it’s a useful tool. If it doesn’t, then maybe it isn’t for you. In my personal experience, I’ve had great success with ERG mode, and can spend 4 weeks exclusively on a trainer and on the first ride back outside have no trouble riding to a target over varying terrain. The only difference is that when not using ERG, I’m looking at my bike computer a little more often.


Turn off power smoothing and you’ll see. No one on TR, or anywhere for that matter, is holding “smooth” power, your body doesn’t work that way. Then consider the 1.5% margin of error for most power meters and that adds another variable. The TR power number appears smooth but there is constant fluctuations over/under the target. It’s just not displayed (on purpose).


I also think it’s funny (upsetting, stupid, lazy… fill in your own superlative) that his screen grab was taken directly from the TrainerRoad Help Center.

That borders on copyright infringement (unless he got permission, which is highly doubtful).

  • Even if it’s not a violation, it’s total crap and shows his total lack of ethics.


But it’s right inline with his last line: “Let’s…play the game." :wink:


I do think there is a benefit to knowing what RPE corresponds to what power zone, so IRL you don’t need to continually be looking down at your power meter. But that’s completely independent of erg vs non-erg. Seems like a clickbait post to me. And seems like it’s working :grin:

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Polarizing post is polarizing…

  • (and we aren’t even talking about Polarized training :stuck_out_tongue: )