RPE Kickr compared to Road bike

I’ve been doing structured Training for six months with a power meter and a coach. Last week’s TSS was 677 and my CTL is 85.
I’m new to Smart Trainers, though. I got a Kickr last month and I’m surprised at how much more difficult the same power level workouts feel on the Kickr compared to my outdoor workouts. I’ve calibrated the Kickr at the beginning of my TR workouts.
One of my recent outdoor workouts included 6 x 1 x max effort intervals and then 4 x 6 x Zone 4-5 intervals. I was able to double my FTP for the max effort intervals and hit all my marks for the Zone 4-5 intervals. However, II know that if I were to try to do the same workout indoors on the Kickr there’s no way I would have been able to double my FTP on the shorter intervals and I don’t think I would have been able to hit my marks and/or complete the longer ones.
Is my experience typical?

  1. What is your cooling situation?

    • You need LOTS of air flow over your body, best from 2 or 3 good fans and fresh air from a window or air conditioning is a bonus. If you are sweating buckets to the floor, you are lacking sufficient cooling. That will severely limit your power and elevate your RPE.
  2. Are you using ERG or Resistance mode for your workouts?

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I had the same experience. Almost 50 watts difference. Maybe mine was broken. Sold it and only work out outdoors or on rollers (Elite E-motion). With the rollers it’s only a little harder than outdoors. Close enough to train at my outside ftp.

RE: Kickr | It’s harder because you don’t get to coast or get micro breaks like you do outside. Adapt to it and see performance gains.

If you are really worried about it, test it versus your bike power meter. Record one to your bike computer and the other to a traditional computer. Grab both fit files and put them in something like Zwiftpower’s analysis. (Why doesn’t TR have this as a feature)

I have great ventilation.
I’ve been using ERG

Tomorrow I’ll use Resistance for the first time as I have 20 second intervals.

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I’m not doubting the Kickr’s power measurement. I’m just surprised by the difficulty and wanted to hear how others have experienced this transition.

Doing my 2 year of indoor training on the kickr.
The RPE is higher when riding inside! - the music is way better tho :smiley:

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Good deal.

In case you haven’t seen it, this is worth the time to really learn about ERG mode.

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I don’t think the psychology of going nowhere indoors gets enough play.


Motivation and/or distraction are well up there in my personal list. Top 5 for sure.

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I use Stages power meter both outside and on the Kickr 2017 (wheel off). Workouts feel the same and I hit the same power targets. I’ve been using resistance instead Erg. More specifically I use Level / Standard mode. I have two modest fans with decent airflow. Mental aspect can make a big difference for me.

In the past I’ve looked at Kickr optical power estimation and my conclusion was that accuracy is variable during the ride. At least if I assume my Stages is more accurate. YMMV.

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I had a similar situation where my KICKR (Snap version) felt like it was reading much lower than my outdoor power. To the tune of 50-60w. I lived with it for a few months and then finally did a factory spindown. Doing this seemed to correct the discrepancy and power numbers were instantly closer to what I suspected they were.

I followed this procedure:

I would do this before chalking it up to A) cooling B) ERG mode adjustment C) Some other thing. I’ve done a lot of indoor training in both cool and warm environments and cooling hasn’t ever led to a massive discrepancy in power or RPE. It might be a mechanical issue with your trainer software/firmware. Try this first.

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It sounds to me as if you’re measuring power indoors with the Kickr and outdoors with your PM.

Comparing these two numbers is not worthwhile. There will always be variations between power meters. Can you use your powermeter indoors too? You can use it to control your smart trainer using Powermatch.

Once you are measuring your workouts with the same PM, then consider all the other variations between indoor/outdoor as mentioned above such as cooling.

Can you expand on this? Are you doing a TR workout and increasing the intensity to 200%? And were you hitting all your marks for z4-5 with that same increase?

My bike on the Kickr doesn’t have a power meter.

I tried using Powermatch earlier with my power metered bike and couldn’t get it to work correctly, the resistance was erratic. I decided to use a bike without a power meter that I could leave on the Kickr. Avoids the minor but frequent hassle of taking my bike on and off the Kickr.

I’ll put the power metered bike back on though and compare the Kickr’s reported power with my ELEMNT Bolt’s reported power. I can use ant+ Connections with the Bolt.

My outdoor workout with 200% x FTP was a set of 1 minute max effort intervals. It was a workout my coach assigned to me, not a TR workout
I didn’t have a target I was trying to match. The six minute zone 4-5 intervals had a target range of watts from high zone 4 to low zone 5. I tried to keep my output within that range by ramping up to that range as quickly as possible without creating huge spikes in the first few seconds.

The reason I mentioned it was to show that I’m accustomed to intense workouts. My question is why if I can successfully complete an intense workout like that does a less intense Kickr workout feel so hard.

Thanks. Good to know.

Kickr 2017 (wheel off, direct drive) and Stages have worked well with PowerMatch. Despite that, I think its more Erg vs Resistance. Erg on the Kickr doesn’t “feel” like riding outside. Outside you can vary cadence and it feels very different than when in Erg mode. So I’ve settled on using Level / Standard mode and shifting gears while on the trainer, as it makes the workout feel more like doing it outside. Same power meter inside and outside. Thats what I’ve found to work well, your mileage may vary.

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Do the advance spin down and compare it to you PM. Kickr is ok until it isn’t. Turn you power smoothing off also. The nice smooth lines are fake.

Where’s the rabbit-hole thread discussing the reality of differences in ERG mode in the small and big ring?

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