20 Minute FTP on Smart Trainer: Resistance Question

On the 20 minute FTP test - when it switches to Resistance Mode, how do I know what the resistance should be set to? I looked in the device settings and the resistance is set to 33 which I guess is default for a Kickr?

Im curious if the resistance selected will result in a different FTP that doesnt correlate to ERG mode.

Yup, that is where you go to set the starting value. 33% is a decent value for most riders, and allows shifting to fine to the actual power when needed.

  • That’s an interesting question, and ‘no’ is the common answer.

But, when we look at things like flywheel speed (which relates to the Resistance setting and the gearing a rider uses to hit their power targets), we can see some potential impact on the “FTP” between max or min flywheel speed. There is no universal answer here. But there is a general sense that people feel a difference in the pedals and possibly muscular loading between max and min flywheel speeds.

If in doubt, the 33% is a good figure and quite close to what I use when in RES mode.


Is resistance roughly equivalent across different brands of trainers?

I’ve been wondering about users resistance settings for a while now. I don’t use erg so am not too fussed on that part of the equation, and I assume/hope that Watts are Watts and that say 200 or 300W should be accurate/the same whether I’m at 15% or 50%?

Watts are watts and if you are on the same device(s) for testing and training you shouldn’t fuss over this.

However - as Chad pointed out - different strokes for different folks. I wouldn’t recommend this for a 20min test, but on another ride/workout or an 8 min test EXPERIMENT. High cadence is better for some people (saving their muscles) where some get better turning a bigger gear at a lower cadence (saving their lungs and HR).

So while watts are watts, you might personally be able to accomplish more watts using one method or another.

You might find that a massive resistance, little gear, and more muscular effort works for you. You might find that little resistance, pushing a big gear and a high cadence works better for you.

Yeah, it’s funny you say that as it’s sort of why I started thinking about it. I was at 20% and went up to 21% to move one gear back up my cassette with my last FTP increase. I recently tried to go to 22% and found the effort significantly different (and I couldn’t get my cadence/effort syncd up.

21% seems low, but I’m pushing out ok-ish Watts so it made me wonder.

Personally when I do a 20min those last few moments are finding any and all means to get another watt. Shifting, resistance, prayers, all fair game.

Offtopic - try the ramp just once or twice. I think it reduces the likelihood of this type of personal variance leaving something on the table for most people. You’ll find ERG works better (or if you use resistance its must less movement) and if you are OK with the results vs. your 20 min, you just got a whole lot easier protocol

My new coach told me to do the 20 minute FTP test.

  • I can’t say for certain, but I don’t think it is consistent if you mean that in relation to the “power” it takes to ride at that percentage setting.

  • My overly simple way of looking at the RES setting is that the percentage is essentially related to the max resistance of the trainer on offer.

    • For a trainer with a 2000w max resistance, 50% would be around 1000w resistance.
    • For a trainer with a 1000w max resistance, 50% would be around 500w resistance.
  • This is what I believe is a past understanding in the world (most often quoted in relation to ERG mode), and one I feel is not correct.

  • As mentioned, I firmly believe that flywheel speed can be something that is at least felt. We have seen many comments from users that they can “tell the difference” in feel of the pedals at the same wattage, but at different flywheel speeds (max vs min and somewhere between).

  • I make no claims that any of this will yield meaningful differences in training effect. I have no real evidence other than my own feelings. As such, I choose to try and apply a flywheel speed that makes sense and aligns with my needs outside on the bike.

  • So, long story story, I feel that gearing matters to some extent, even if the power is identical.

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I’d recommend experimenting before doing the FTP test. My FTP is around 250W and 33% is a good place to start experimenting on my Kickr 2017 direct-drive. Free Ride is a good workout in the TR library to use for playing around with resistance until you find a good combo of resistance and your personal preference for cadence on a 20-minute hard effort.

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As above, have a couple of test (short, not 20min!) at different resistance levels.

I think it probably doesn’t matter for riding at FTP (unless it’s extremely high or low), but the resistance level might be more important for sprints etc. I think it should be set so that you can hit all power levels with your existing gearing, without hitting any power floors/ceilings.

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Thanks for the suggestions! I did the free ride luckily. The gear I had it in would not have worked. Did the FTP test and my FTP increased by 11% in 12 weeks.

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I hate the 20 minute test but I always think I’ve over-paced it. Nailing it is going to be 20 minutes at 105% which is just hard for a long time. If you start off too optimistically then you are screwed 10-15 minutes in to the test.

I’ve enjoyed the kolie moore baseline test (35-45 min) much better since it’s a ramping effort. You also feel like you really found your steady state.

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I experimented myself and found the 2x8min was my fave. I’ve since gone to the ramp test just for the quickness of it all but frankly haven’t seen as great of gains (which I attribute to many other things).