Login required to started new threads

Login required to post replies

Subjective exhaustion on different trainers
Quote | Reply
hi everyone,

this is not a post about power difference measured by different power meters.
it should be about the subjective feeling when it comes to same power output on different trainers.

this is my story:
I recently upgraded from a wheelon (elite novo mag) with a garmin vector 2 to a kickr core 2018 (refurbished).
from a first glance, the garmin measures slightly more watts than the kickr core
(i do understand the concept that garmin measures in the pedal and the kickr in the rearhub and due to friction there is a loss of power)

but now comes the plot twist:
the same wattage output (220 measured by the kickr, 230 by the garmin) feels way easier on the kickr than on the wheelon (230 measured by the garmin).
does anyone share the same experience?

Thanks a lot

Marius
Quote Reply
Re: Subjective exhaustion on different trainers [trisomemari] [ In reply to ]
Quote | Reply
Are you using the same gear for the same watts?
Usually the inertia of the trainer tends to change how hard it feels. Also the size of the trainers flywheel
Quote Reply
Re: Subjective exhaustion on different trainers [trisomemari] [ In reply to ]
Quote | Reply
trisomemari wrote:
does anyone share the same experience?

Sure. Different trainers will have different inertial load even at the same power level. Some people (not all) are more sensitive to inertial load than others, so even at the same power they'll use different gear ratios and cadences. A clearer example is for people who switch between rollers and a trainer: the inertial load is very very different so even at the same power almost everyone will use different gear ratios and cadences.

This, by the way, is the reason you shouldn't take your "preferred" cadence from a trainer and try to transfer that to the outside world. You shouldn't even take your preferred cadence from one trainer and transfer that to a different trainer.
Quote Reply
Re: Subjective exhaustion on different trainers [trisomemari] [ In reply to ]
Quote | Reply
Echoing the comments above, the trainer's braking force greatly affects how the trainer feels. If the wheel is moving slower, then the trainer has a higher braking force. A higher braking force means that you are experiencing more force throughout the pedal cycle, which causes more muscle engagement at top end bottom end of the pedal stroke. This will wear you out faster than lighter braking force against a faster turning wheel.

Edit: GPLama illustrates this in one of his videos by showing the power phase differences in the pedal stroke as a function of gearing on an ERG smart trainer.
Last edited by: exxxviii: Dec 4, 19 10:25
Quote Reply
Re: Subjective exhaustion on different trainers [exxxviii] [ In reply to ]
Quote | Reply
Thank you very much for your quick response everyone.
So what does that mean when it comes to the power output I can sustain for 1h?
I knew that it would differ between different power meters (just because different technologie, points of measure etc.) but I was unaware that it'll differ with the same power meter (in my case vectors) if I ride a wheel on, direct drive or outside.
Quote Reply
Re: Subjective exhaustion on different trainers [trisomemari] [ In reply to ]
Quote | Reply
trisomemari wrote:
So what does that mean when it comes to the power output I can sustain for 1h?
Ideally, you would train most similarly to how you would race. So, in a race, you are likely to be riding 20+ MPH at your target power. So, when doing an FTP test, I would ride in the gear most similar to your training conditions, like a 52x16 gearing.

Here's the problem with that... TrainerRoad recommends a lower gear for better power accuracy and trainer responsiveness (lower flywheel speed). Riding at a lower speed has a different muscle recruitment.

Therefore, I would do your FTP test the way you would train. So, if you are likely to train in something like a 36x16 (what I do), then I would do my FTP test in that same gear. Then, all of your workouts that index to FTP would be sound. The problem would be that your training FTP may not be a perfect match for your outside ride FTP. That said, it probably does not matter. You will figure out what your best %FTP is for a race, and if your trainer FTP is low, you might race to a higher %FTP than if you did your FTP test outside.
Quote Reply
Re: Subjective exhaustion on different trainers [trisomemari] [ In reply to ]
Quote | Reply
trisomemari wrote:
TI was unaware that it'll differ with the same power meter (in my case vectors) if I ride a wheel on, direct drive or outside.
A few more thoughts on this...

FTP is not a fixed thing, like saying you bench pressed 250 lbs. It is more conceptual, because you are using a shorter test to theoretically project what you might do in a one-hour all-in effort, which is also conceptual and subject to conditions.

So, the key is understanding that FTP is just a tool to help guide your training and racing, but it is not an absolute. An indoor ramp test, an indoor 20 minute test, and outdoor test on a flat, and an outdoor test on a climb would all likely produce different FTP numbers.

IMHO, FTP is most valuable is a training guide. Programs like TrainerRoad test FTP and then use that to index all of your workouts. It does not matter if FTP is perfect as long as it adequately drives workout efforts that make you stronger. TrainerRoad does this really well.

On the other hand, if you want to know FTP for bragging rights, then I would do an FTP test on a 8% - 12% mountain climb on a cool morning. For me, this produces an FTP about 20W higher than an indoor trainer ramp test.

My other important use for FTP is guiding me to my race target power. But again, it is just the initial input that I then refine with actual race experience. For example, on an HIM with a cool run, I learned that I can ride a little over 80% FTP as measured on an indoor ramp test. But, if the run is hotter (in the 90s), then I need to ride around 75% FTP from my same indoor ramp test.
Quote Reply
Re: Subjective exhaustion on different trainers [exxxviii] [ In reply to ]
Quote | Reply
exxxviii wrote:
trisomemari wrote:
TI was unaware that it'll differ with the same power meter (in my case vectors) if I ride a wheel on, direct drive or outside.
A few more thoughts on this...

My other important use for FTP is guiding me to my race target power. But again, it is just the initial input that I then refine with actual race experience.

this is what it is about for me. gained experimce with my garmin the wheel on for 4 years. now this is a new situation i need to adapt to.
now would probably increase ftp value in zwift by 20ish watts just to compensate for PM difference and less exhaustion and see how it goes for the next weeks.

thanks a ton to all of you
Quote Reply