Can someone school me on Erg mode?

This is my fourth session trying to use Erg mode on a smart trainer, after a few years powertap single sided pedals and a dumb Tacx Boost.

And fourth time it’s done me in.

Basically I’m trying to just hold a cadence and let the erg do the intervals - 10mins at FTP today.

Pedals are powermatched to Elite Zumo.

Even in the first interval you can see the power is spiking, I’m not perfect cadence wise so I assumed it was me. Second interval I started to suspect something was wrong because it seemed to get suddenly very hard while I was being consistent on cadence. Third interval it was monsterous. By then I was tired so maybe it was still me, but I’m sure I was holding cadence and it would make me go for ages at 280, 290, over 300 instead of achieving the target 250.

Also, I think it’s weird you can see the graph is spiking way over but both first and second intervals claim to be bang if target…is the Erg making me work harder for previously missed Watts to achieve the average for the interval, rather than just working harder for lower cadence?

Cheers,

Joe

Just looking at your graph tells me ERG isn’t activated.

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The setting is set there in the configuration for the Zumo in TR, and the turbo is adjusting resistance based on cadence.

Is there anything else you might suggest I’ve missed?

You need to hold a smooth cadence, every time you change that the resistance has to change to make up for it, and causes big spikes. Some spikes while using PM are normal though. The first interval and the first half of the second interval look surprisingly smooth for how jagged your cadence line is honestly.

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image

That portion looks normal to me. I’m a Kickr wheel-off trainer and use PowerMatch with Stages crank based PM. Technically speaking, it is probably smoother than if you turned off Erg (and far smoother than doing intervals outside in perfect conditions).

Your cadence (white line) does look a little bit more variable than mine, especially in Threshold 2 and Threshold 3.

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What gear are you in? In erg, you can in theory ride in any gear but erg mode can feel and behave differently depending on your gear choice. As the flywheel on your trainer spins faster, it has more inertia and thus smooths out power fluctuations and its not quite as sensitive to small cadence changes. On the other hand, if you use too big a gear, you can kind of overwhelm erg mode. I find small gears to be super sensitive to cadence fluctuations.

Try some significant gear experimenting changes on your next ride and see if that changes things. If you’re in the small ring, try shifting up to the big ring and vice versa

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Now that you mention gearing, it actually looks like the OP may have been shifting gears while in ERG, which would definitely ruin the power graph. The only other thing I can say is OP says the interval got very hard, which sounds par for threshold intervals in ERG, especially if you’re not used to how ERG forces you to hold the power with no mercy.

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I’ll also throw in that if the interval starts to get hard and you thus decide to shift to an easier gear, that can be a great way to end up in the dreaded erg spiral of death. If you need to make things easier, change the intensity setting - shifting does not lower the required power and the brief cadence change can actually make things harder.

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Looks to me like way too much variance in cadence, and a lot of it is choppy, so maybe shifting gears? But my cadence line almost never has that much variance unless I’m trying to.

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The spikes in Power are normal. Kickr trainers have ERG mode smoothing on ( this is turned on by default), not sure about other brand of trainers, this makes their power reading look smooth. Power is not going to stay smooth even in ERG mode, if that is what you’re looking for. I believe the lows are you stopping. At the end of your interval if you power is on target you are good. True power is never smooth or going to smooth across. Just make sure you hit your target at the end of the interval.

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You want those pretty smooth lines don’t you?

But here you go:

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Did you do the intervals in the small ring? from my own experience doing intervals in the big ring tends to be much smoother

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i would also disable powermatch to start

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Why do you suggest this? It only changes how the power graph looks, it doesn’t affect the actual average power for the interval, or how resistance is applied.

The TR power smoothing only affects the number that is displayed in the UI, not the appearance of the graph.

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Wahoo power smoothing does not change the underlying data but does create an artificially smoothed line, can hide data in the graph which might be helpful in sorting out an issue. IMHO Wahoo smoothing should be turned off.

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I’m not that experienced with smart trainers but as you know I have the same one as you and my cadence line doesn’t look like that at all. I do occasionally change gear but it’s only a 1 cog shift and I always use the big ring.
As others have said, you have to be so consistent with cadence, slowing by just 5rpm seems to make things sooo much harder. Maybe do a few sessions at tempo, in the big ring and really concentrate on cadence.

@JoeX. Are you using ant+ or bt? Also what platform?

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I use a laptop with an Ant+ dongle. @ericallenboyd sorry I thought that was @JoeX asking

Here’s a recent session

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