True power difference between wheel based dumb trainers and direct drive smart trainers

About me: Triathlete thinking about switching to bike racing. 6’6" tall. 185 pounds. FTP: 340 (Virtual Power on KK RM)

Ok… so I’m still in the stone age of cycling. I’ll admit it. But I’m super cheap, and I just can’t justify the the cost of a power meter or a smart trainer because of how effect virtual power has been for me on a KK Road Machine since I started with TR in 2013. It keeps me at the pointy end of most group rides and I can easily ride under an hour for a 40 mile TT; and I can outclimb most riders I go up against…

But I’m wondering if I’m losing something significant by not using a smart/direct drive trainer and/or a power meter. My structured workouts are all on Trainerroad. When I ride outside, it’s either to just get some endurance riding in with no hard targets, or to do a group ride where I want to test myself against other athletes (and so - in theory - power doesn’t matter as much). I like the contrast between unstructured outdoor riding and super structured indoor riding… and I feel like the rear wheel trainer provides power reading that ought to be “close enough” to a smart/direct drive trainer.


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  • I doubt you are losing anything.

I have splurged on a plethora of power meters and smart trainers in the last 5 years. It’s largely because I have access to employee purchase deals through my side job as a bike fitter. Otherwise, I would likely not have much (if any) of the silly toys that I do now.

With Virtual Power, you are getting a repeatable and quantifiable value of your training and fitness. It is a “tape measure” you can use to set training targets and gauge fitness over time. Assuming you are consistent with the tire model, roller pressure and tire pressure, you will get consistent data over time. That is all you really need, IMHO.

Yes, power data from outside (added to the inside data from VP or real power) is nice to have for tracking TSS more accurately. It can also be used for certain cases in racing and other events, but those are possibly secondary to the training emphasis.

If you have used your time on the trainer with VP to also inform your perception of your relative efforts strengths and weaknesses, I think you are all set. The RPE value is one I find more useful in the moment than any power meter or HR data. Your gut and how you feel in the moment matters, regardless of the numbers some days. Yes, power is a solid reference, but it is not perfect in it’s use either.

I think it sounds like you have yourself well dialed in and are not missing out at all.


Agree with @mcneese.chad; the bulk of the gains come from training at the right level. A new trainer won’t help you do that any better, especially since you have a very solid “dumb” trainer that is serving you well.

If you were to drop cash on anything at all, a power meter would be a better choice over a new smart trainer, especially if you use the same bike on the road as on your trainer (or can readily swap the power meter over). A power meter can help by letting you gather data from real rides, pace better, estimate energy output if that’s important information for your nutrition, and by making sure you’re not overestimating or underestimating how hard your outdoor rides were (for purposes of ensuring sufficient recovery). All of this can be had for cheaper than a new smart trainer. I personally have had good luck buying secondhand Stages units that fit my crankset.

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That’s sound advice. It’s what I’ve come to believe when I’ve been tempted to shell out the $$$ for a power meter or “better” trainer. I feel like results are results, and it doesn’t matter as long as you (fairly) get them. I’ve become so accustomed to the use of TrainerRoad and the Base-Build-Specialty routine; and my performance continues to trend upwards even after 6 years of use.

Also good advice on the second-hand PM. I may consider that for a future option. FWIW, in spite of the many years of TrainerRoad use, I still tend to underestimate my RPE when I’m riding with other people. This was evidenced when I recently did my first couple road races ever, and I ended up coming out of them wayyyyyyyyyy more fatigued than I thought I would (I attacked several times and burnt a lot of matches trying to bridge to a break). So using a PM to moderate my efforts when I attack might be a wise choice…

Until I decide to get one, I’ll just keep reaping the benefits of what TR does so well for me. =)

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I assume this is a 40km TT, otherwise you are running 9.3 miles faster than Merckx’s hour record and should head for the track right now.


I agree with the sentiment, if you’re getting good training in then you’re not “losing out”.

However, I saw significant benefits moving from virtual power to power meter pedals. All of a sudden my output values were more consistent, not flickering up and down so much, this made me more positive when staring at the TR screen. I could see useful info about my outdoor rides and racing that really changed my view on how I performed. I could simulate race efforts, execute in races according to a plan, rather than by feel.

So, lots of benefits imo, did they win me races? No. Did I train better/more often? I think so. Was it worth the $$$? To me, yes.

As has been said, legit power meter: bueno; bling trainer, not so much.

I got a power meter intially because I lost faith and patience with my Road Machine’s virtual power. Many seemingly minute things can effect the power estimate, including the temperature of the silicone, which means warmup and spindown EVERY ride.

With a power meter, the silicone temp, tire pressure, and roller tension may change the feel, but not the accuracy. Plus, no mandatory warmups.

Agreed. Yeah… the silicone does require the warmup. But I’ve found that I’m quite satisfied with the consistent system I’ve been able to maintain with tire pressure, consistent tension and the line. It works for me.

It’s nice to know I’m not missing out on anything super big. Heh… all that marketing must be getting to me.

You are fine with the KKRM and VP. I have the same setup. What matters is putting in your best effort and following the plan.

If you were to spring for a power meter or smart trainer I recommend the power meter because you then have power on outdoor rides as well. It is a better option.

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I have been training for years with a KKRM and T.R. using virtual power with my “trainer bike”. My outdoor bike is equipped with power pedals that I have never been motivated enough to put on my trainer bike. As long as I was consistent with bike setup, tire pressure etc., training inside with a “dumb trainer” was just fine.
Then, I just purchased Kickr Core smart trainer a few weeks ago. I did my recovery week in the middle of general build on the new trainer and noted some muscle discomfort that I had not experienced on he dumb trainer. Definitely was experiencing different muscle recruitment patterns, but the experience of riding with the flywheel on the smart trainer felt more like riding on the road. Did a ramp test and my power was down about 12% compared with the KKRM. No worries, as this was virtual power vs. a more accurate assessment of power on the Kickr. An additional benefit of the smart trainer was the ability to “fine tune” my cadence without shifting gears in erg mode, while at times I was not able to find the precise gear combination to achieve the right cadence on the dumb trainer.
So the question is: will I be able to achieve more ftp gains with a smart trainer or will my senescent and declining neuromuscular capabilities (age 66) impair my further progress.

I’ll be curious too! I’d love to hear back from you a few months down the road too see what kind of impact you experience from using the snap v. the road machine. Thanks!!

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Sure, but it was Kurt Kinetic Road Machine dumb trainer and now a Kickr Core smart trainer.
Ouch! 9-3 minute 115% VO2 max intervals this a.m.