From time to time when I’m doing anaerobic workouts in erg mode I’ll have intervals where I’ll start the interval with a large power spike (not always intentional) and I’ll spin like crazy and erg mode won’t bring up the intensity. It’s great to work on high cadence, but at the same time it means it’s hard to stay on the power target.
A good example was the last interval in my workout today (TR, you have permission to look at my profile if you want):
Most of that interval I was spinning between 120 to 140 rpm. 120 is normally my comfortable cap but I was having to spin higher just to try to pull the power back up.
That said, I could have just shifted up a gear or two, still be spinning around 120, and hit the power target. But I don’t know enough about erg mode or how the data is captured to know if that’s going to goof readings up or something. I’m assuming no on the power input b/c power is power, but I don’t know if that’s going to make the trainer go bonkers in the middle of an interval or something.
Also I know I could just do the workouts in resistance mode and I used to do that all of the time, but I found that doing them in erg mode kept me from over burning on intervals and led to uneven workouts if that makes any sense.
But yeah, would shifting in erg mode goof stuff up? I know I can just try it, but I figured I’d ask before I potentially screw up a workout.
If you shift and keep pedaling, the resistance will quickly adjust to maintain the set power. If you hold the same cadence, not much changes except the trainer flywheel will be spinning faster or slower depending on which direction you shifted. Where shifting in ERG mode can come in handy is if you want to make a big cadence change. Let’s say you’re pedaling at 90 rpm but want to stand and pedal at 60 rpm. If just do that, the initial resistance will be low for standing and it’ll take a bit for the trainer to increase resistance for the lower cadence. Instead, just before standing, you can shift to a couple or three gears harder, then stand. The trainer won’t have to adjust resistance as much since the flywheel speed won’t have to change much. The same works when going from standing to seated and wanting a higher cadence. Sit and simultaneously shift to an easier gear and pick up your cadence.
I read somewhere something once about what gear you’re in in ERG mode supposedly does affect how the flywheel spins and therefore the feel of the pedals etc but I’m not sure I’ve noticed much except for right when you shift. Then the ERG function catches up with you and it feels the same again.
I would love to hear from someone on here that knows something about this though because I have a KICKR bike and it WILL NOT let me go below 54 cadence. If I let the cadence go below that it “let’s go” and I spin out and the ERG Mode takes a while to latch back on and get the wattage back up. It drives me crazy trying to do torque work either seated or standing.
I’ve tried doing it in different gears but the same thing happens no matter what gear I’m in.
Shifting isn’t really any different from erg adjusting resistance for an interval. It’ll read what power you’re doing, what the target is and adjust if the algorithm says to do so.
because it takes a little bit for it to adjust, you could time a shift just right if you’re really trying to get on target asap. You can also lower cadence before an interval, and then spin back up just before the interval starts, such that erg is still mid adjustment when power changes. Will probably vary a bit between different trainers.
And cool, it sounds like I’m not going to screw up my interval or workout from shifting in erg mode. I’ll give it a try the next time I’m spinning a high cadence on a short interval and the trainer isn’t pulling the resistance up fast enough.
It’s hard for me to tell exactly from your video (as I can’t figure out how to pause it), but it sort of looks like your power spike at the start of the interval might be due to your increase in cadence, as opposed to letting the trainer increase the resistance. And then, once you start the interval, you’re just keeping the high cadence, which keeps the power up without a related increase in resistance.
What happens if, instead of increasing your cadence at the start of the interval, you just stay around the same cadence, and let the trainer increase the resistance to achieve the power target? (And if the trainer isn’t increasing the resistance, there might be an issue with your trainer, or it might need calibration.)
You are doing ERG mode wrong. You have to give time for the trainer to increase the resistance to meet the new power target in the interval. If you spin at 120rpm it will only provide enough resistance to meet the target power at that cadence as long as you are maintaining that cadence.
By all means spin up a second before the interval starts to prevent erg spiral of doom but keep your cadence constant and the ERG will provide the resistance to match.
out of interest what gearing are you using? ERG mode is slower to respond when the flywheel is spinning fast when you are in a big gear,.
I ride primarily in ERG mode indoors so I can “shut my brain off and do the work” when I’m still half-asleep at 5AM. I also read somewhere that running the chain in the big ring is harder on the fly wheel of the trainer itself (and the big rings are of course much more expensive to replace when worn out than the small) so for the past 2 years or so I’ve been riding with my straight chain line in the small ring. The spin up and down after intervals feels “smoother” to me and I rarely shift except for during super hard intervals where I finish almost dying a death-spiral and I have to give it a gear or two easier once I hit the rest interval to get a head start to keep the pedals moving. If I’m doing super short high-wattage “on-off” intervals I will chose the big ring because it feels like it allows me to hit that power target in time. For the most part though as I get within a few seconds to the next interval I will ramp up or down to my preferred cadence and then once I hit the interval let the trainer do the work at adjusting the power. There is definitely something to be said about trainer calibration if you have the option as well.
This means that as your cadence changes, your torque needs to change to stay on the power target. To get more torque, the trainer needs to increase resistance.
The key to ERG mode is steady cadence. While it’s okay to change your cadence for different intervals, I always recommend getting set in your desired cadence around 5 seconds before the interval starts. That way, your trainer will only have to increase the resistance steadily to find the power target. If you continuously change your cadence, the trainer will constantly adjust resistance to keep you on the power target.
Steady Cadence = Steady Power
In terms of shifting gears, it does make a subtle difference in the ride feel. Higher gears create a higher flywheel speed, which adds momentum to your pedaling. It creates the feeling of pedaling downhill (at least in my experience). Lower gears keep the flywheel speed low, and allow for quicker adjustments in resistance, and also keep more torque on the entirety of the pedal stroke, which feels more like climbing to me. This is why we recommend using low gearing when training indoors (small chainring if you have more than one, and a cog at least halfway up the cassette, while keeping a relatively straight chainline).
Think of it like a car moving at a higher speed – applying the gas or brakes doesn’t feel as snappy as it does when traveling at a lower speed. There’s simply less momentum to overcome at lower speeds. Not to get too into the weeds here, but that’s why, if you look at a car’s power curve, the torque typically dies off at higher RPMs, which is where power takes over.
For an indoor trainer, we’re looking at torque, so you want low flywheel speed for a more responsive feel and more tension on the chain to train all of the muscles used when pedaling.
