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Smart Trainers- interval workouts- Unwanted resistance issues

Old 05-20-20, 09:49 PM
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Cykilist2
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Smart Trainers- interval workouts- Unwanted resistance issues

I'm new to smart trainers and the apps. I have a Saris H3. I'm finishing my first evaluation of a platform (Rouvy), and attempted two power surge workouts... You start with a warm up (150-170), surge to 300% of that (600 about, 130cadence), then settle into an elevated level (170-185), surge to 300% of that (600 again, [115 max cadence] but kept it only for a short spell, because unwanted resistance kicked in, dropped back down to 170-185). On the third 300%er, the resistance was so oompossible, I was churning only 400, with cadence at 75 max, which ain't gonna get you 600 power numbers. I also stopped the workout at that point, because the trainer was doing things that I did not want it to do.

I mentioned this in my post ride comments, and one of my riding buddies mentioned something called an ERG death spiral. I did a little reading on it, and it sounds like it might be the problem, but I'm not sure how to circumvent it and be able to have an interval workout without having all the unnecessary resistance, that I do not want in this type of workout.
Both power surge workouts ended prematurely, but doing Alpe du zwift, no problem!!!

Those of you that do structured interval workouts, is there a certain mode you put your smart trainer in so you can get to your 300% power numbers when the workout calls for it?
Does the problem lie with a setting on the H3?
Does the problem lie with the Rouvy app, and will I have this same problem using Trainer Road, zwift, bkool, etc? I'm trying to evaluate training platforms right now, and don't want to be discouraged from doing structured workouts, which I do enjoy periodically.

Thanks for your suggestions.
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Old 05-20-20, 10:01 PM
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you really have to be careful not to let your cadence drop, because it's incredibly difficult to power your way out of the problem, unlike outside.
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Old 05-20-20, 10:15 PM
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How do you do your training then? Just even one drop seemed to create a problem Keeping a certain level, I am not able to do consistently. Is there a setting where I have that "play" so the resistance doesn't kick in?
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Old 05-21-20, 01:43 AM
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Are you running into the problem of resistance kicking up until you have no strength to push the pedals (i.e. the ERG death spiral), or that no matter how hard you push it's hitting a power cap?

From your description it sounds more like the latter than the former... so assuming that:

1) make sure you are not using a gear combination that is too light (e.g. 34t front 28t back for high resistance work). Some trainers, even though able to handle large amounts of maximum power (I checked your Saris spec, it does up to 2000W), but if the gear is too light it may be unable to supply the necessary resistance to handle the effort.

2) if the surge efforts are too short, you may be experiencing lag. Basically there is a delay from when the app tells the trainer to increase resistance, to the point where the trainer actually starts increasing resistance, and this lag can sometimes be as long as 3-5s especially if there is a lot of wireless interference in your area. So by the time the trainer registers the change, it may already be time to end that effort and adjust to the next one. Some apps, such as The Sufferfest, recommend turning off ERG mode for these sort of workouts and manually adjust your efforts by changing gears instead.
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Old 05-21-20, 11:06 AM
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I thought TrainerRoad had implemented something to avoid the death spiral. Seems like it doesn't really clamp down if you are more than about 10% low. I noticed this with bluetooth on my android tablet. Now, because of Zwift, I'm using ant+ on a PC for TR. And it does seem more prone to death spirals. In either case, getting back up to full power has always been a struggle though.
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Old 05-21-20, 11:22 AM
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ERG Death Spiral.... Methinks

atwl77: Yes, I believe that's the issue. The moving of the pedals becomes just about impossible, when the workout calls for a surge in effort. It's certainly not lag. the resistance never dials back. It just gets worse and worse.
It seems like I need to turn off ERG mode for these type of workouts. All I want to be able to do is match the power numbers the workout calls for. It's good training. If I want resistance, I'll set up a workout that way, or I'll do another trek up Alpe du zwift
I also believe you can, in most apps, set up workouts where you can call for a set resistance for a period of time.
unterhausen: It shouldn't be a struggle. I think we're both in the same boat. I ride too much!
I'll see if I can find the setting for "Free mode" in the Saris settings.. I believe it is there. I'll just go between, when I'm set to do a 1 hour workout.
Thanks for the clarifiation.
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Old 05-21-20, 12:43 PM
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Don't do workouts like that in ERG. Do threshold or pursuit power or less. It's just too wild a swing too quick. Just set it into the mode where you would change gears on the bike to vary the resistance instead.
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Old 05-22-20, 05:10 AM
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Can't speak to the Saris on Rouvy, but on my Wahoo Kickr on Zwift the key to avoiding the ERG death spiral in any workout, including intervals, is to keep cadence a bit higher than I would do in the real world - essentially to downshift a bit earlier.

If you think of each interval as a hill, get your cadence up (downshifting a gear may help) before you hit the hill. For me on my trainer, anything above 80 rpm keeps me safely away from the death spiral but if I don't increase above that before the interval kicks in, the dip below 80 can be hard to recover from - the death spiral.

Zwift makes it easy to turn ERG mode off, but then the hills on the course drive resistance and that doesn't match what I'm trying to do on the workout.
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Old 05-22-20, 11:01 AM
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I think it would be really difficult for me to hit 600 on my trainer if I weren't in erg mode. OTOH, I can keep my cadence up at 600 watts for only about 15 seconds and then I blow up. I did a couple of weeks of workouts like that last summer, thinking of it as being equivalent to weight training. Didn't seem to help me much. I enjoy it though. I have come to the conclusion that HIIT to do any good has to extend past 30 seconds/interval. Preferably a minute. If I wanted to increase leg strength, the best thing is probably to go at a wattage where you can recover from the trainer bogging down. So nowhere near 600 watts, at least in my case.
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Old 05-22-20, 01:44 PM
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Originally Posted by burnthesheep View Post
Don't do workouts like that in ERG. Do threshold or pursuit power or less. It's just too wild a swing too quick. Just set it into the mode where you would change gears on the bike to vary the resistance instead.
+1. Try it w/o ERG mode. I wouldn't use ERG for shorter stuff. It's controllable through the your interface app (rouvy/zwift/TR etc)
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Old 05-22-20, 01:45 PM
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Also another H3 user in San Diego here . Rode it a couple times this week but i'll be outside this weekend.
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Old 05-23-20, 10:49 PM
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you know, smart trainers really aren't smart. infact they can be down right dumb. they only implement a PID loop inside when in erg mode. in erg mode a target power is defined and the trainer will run the loop increasing or decreasing resistance in order to maintain the target power. it is the application that makes these things smart. it is doing what your application told it to do but you simply can't keep up. i don;t mean that insultingly so don't take it that way. pretty sure i cannot do 300% on the third do let alone the first go so kudos to you there. i also could never peddle at 130, my knees wont permit that.
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Old 05-25-20, 11:05 AM
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Just observing again that trainerroad appears to have some anti-death spiral logic in it. I was having trouble keeping up the other day and it definitely softens up the control if you aren't within about 10%. They must have some kind of death spiral detection. They definitely have some annoying PID behavior left over, I particularly am annoyed at having to push pretty hard after an interval is over if I didn't quite keep up at the end. I usually let it pause the workout. They clear out the integrator term so it's not as difficult to start up
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Old 05-25-20, 03:39 PM
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Originally Posted by unterhausen View Post
Just observing again that trainerroad appears to have some anti-death spiral logic in it. I was having trouble keeping up the other day and it definitely softens up the control if you aren't within about 10%. They must have some kind of death spiral detection. They definitely have some annoying PID behavior left over, I particularly am annoyed at having to push pretty hard after an interval is over if I didn't quite keep up at the end. I usually let it pause the workout. They clear out the integrator term so it's not as difficult to start up
AFAIK there is no way to clear out the I term. It is not in the Ant+ spec. TR likely changes mode from targeted power to simulation. This is what I do in my own app. At the end of interval training I switch from “erg” mode to simulation @ 0% grade. I’ve noticed that my kicker seems to remember what it was doing the last time it was used. Maybe my imagination.
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Old 05-26-20, 10:32 AM
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That's interesting about the spec. I don't think it's your imagination about startup, although it's hard to say what exactly it's remembering. I was trying to adjust my front derailleur the other day and pedaling was impossible. Didn't feel like going to get my phone to release the resistance.
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