Hi all,
I found that workouts done in ERG mode are noticeably easier than the same workouts in resistance mode, specifically SS up to VO2max. For example, the RPE for a 4x10 threshold workouts might be 7/10 on ERG but 9/10 on resistance mode for me.
I’ve only seen people comment on how ERG feels more difficult, so is something wrong with my trainer or the software? Thanks!
Same gearing?
I find erg harder as it locks you more closely into the power and if you let the cadence drop then you need to fight the death spiral as you tire.
As @ibcoleman noted, are you doing anything obviously differently? What’s the trainer?
Cadence. I find it much easier to hold higher cadences and for longer on erg. On simulation and resistance modes, my cadence drop faster. I’m also likely to be in between cadence ranges either spinning too fast or on the low side on simulation and resistance mode. The fatigue is just different.
Aside from the other comments above, maybe ERG is less mentally taxing?
In ERG you just aim to hold a cadence. In resistance mode, you also have to concentrate on the power numbers and adjust your effort level accordingly.
That could play a part?
I have to vary the gearing on resistance mode, but generally around the same gearing as ERG. Would it be easier on ERG if I was in the small ring?
Thanks for the comment. I’m not doing anything different, aside from necessary gearing changes for intervals on resistance mode e.g. dropping to the small ring during a rest interval. I’m on a late 2018 Wahoo Kickr.
I thought about that too, less cognitive load. But the difference is night and day, it makes me hesitant to believe that just the mental part can contribute so much to the RPE.
I ask because my previous trainer was a Tacx Vortex that would read a bit high in the little ring but much higher in the big ring. I was crushing my FTP tests, but always in the big ring and spinning at 110 rpm. Was quite a comedown when I got my (current) trainer a CycleOps H2.
Smaller ring might actually be harder than big ring because you have less flywheel speed and therefore less momentum. I recently had my Kickr 17 crap out on me and forced me to use my old fluid trainer. At easier efforts the fluid trainer felt easier as it seemed to have more momentum than my kickr in erg and in the small ring. As the intensity went up it felt harder on the fluid trainer because hitting the power targets required managing my gearing and cadence and meant I had larger spikes in power due to trying to find the optimal gearing and cadence.
Now big ring in erg has much more flywheel speed and may be the easiest option since you have more momentum from the flywheel and the benefit of not chasing gearing and cadence combinations.
I have the quite opposite effect. My ride last Tuesday was almost sabotaged by ERG. After the first 4 minutes, I could hardly keep spinning, and after turning ERG off, barely recover to finish the set. Repeated the same set two more times with no problem.
That’s not the first time I’ve struggled with it either, but it was the last straw. I’m finding anything above 80% starts to be problematic for me, and feels considerably harder. I am capable of holding target power really well, so I don’t miss ERG. I can still use it for recovery rides with shorter intervals so I can zone out and watch something. Strangely though, I used ERG for the entire on TR last year, so not sure what changed now.
This is my perspective too. Erg means I can tune out and just focus on steady cadence vs worrying about if I am holding the power well.
if you do sweetspot work on resistance mode (or out on the road), you will spend some time over the target power (and some slightly under too). Time at or above FTP is a lot more taxing than power just below it (at sweetspot). So you may finish a workout with several minutes at FTP or above.
Personally I agree with you; I find sweetspot work on the trainer easier in erg mode. But I attribute this to being “Locked in” to a power I should (theoretically) be able to hold for a long time without fatiguing.
I think it is mentally easier too. Yesterday I was out on the road doing some sweetspot and although I hit the numbers ok, the cognitive load of corners, overtaking other cyclists ect. meant it was a lot more draining.
My personal observation (and maybe I am wrong, but this is my feeling) ERG mode is easier because I can recruit power the same way all the time. For a half a year I am doing all my training in a level mode as I need to “chase” the power sometimes and I have a feeling that I recruit more muscles (or at least recruit them differently). Not to mention that after doing all my work in ERG mode I had a problem with putting the same power on the road.
On the other hand with ERG there are no micro-brakes with power fluctuating and during very long sessions (like 1x120@90%) this can lead to harder session in terms of RPE.
Maybe it’s just because I’ve lost power, although I do feel faster/ fitter, but my FTP with ERG is circa 20w lower than with resistance mode for the same perceived effort. With resistance mode I don’t have to worry about getting dragged momentarily into the spiral of death and could get more power out in the long run. 
Maybe the rpe is lower since your not trying to figure out how much to hurt, you just can hurt and not worry about it.