Comparing Garmin FTP estimate with Ramp Test?

Has anyone seen major discrepancies between their Ramp Test results and the FTP estimate on their Garmin? I am fully aware that the Garmin merely provides a rough estimate and is less scientific than a dedicated test, but the Garmin is coming up with values about 30-40 watts higher.

A little background: I’m a non-racer who has been riding outside all summer, and I’ve seen my Garmin estimate slowly creep up as my fitness has improved. Now that I’m integrating the trainer inside back into my rotation, my first ramp test ended up being much lower than I thought. I’m going to recalibrate my Flux and give it another go this week to see how much of it was my lack of preparedness for the test, but I was curious if anyone else has seen large gaps in these FTP values like this.

As long as I do some harder efforts the Garmin estimates close to my 20 min tested FTP. I always ignore it but it’s close…within 5 watts usually. I have a friend that also sees the same thing although he ignores it as well. Take another test.

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Yeah, the test was already on the schedule. The odd thing is, doing a couple of workouts at the higher FTP value from my Garmin was still feasible, so maybe I’m just that bad at testing. We’ll find out this week I suppose. :man_shrugging:

It sounds like you have multiple variable going on:

inside power meter vs. outside power meter (different devices can easily be 20-30 watts apart)

inside vs. outside (people usually make more watts outside)

Other than it strokes your FTP ego, I’d ignore what Garmin estimates.

I have a Fenix 5 and a 530. After hundreds of rides with both I find no value in the FTP estimate from Garmin. For me it is chronically low relative to my 1 hour FTP test, 20 minute FTP test, 8 minute FTP test and TR Ramp test. All put me roughly in the same spot whereas Garmin usually is 10-35 watts lower. I stopped looking at it after I won a race with a pretty big field and set all kinds of power PR’s. When I hit end ride my Fenix 5 greeted me with the “We have detected a lower FTP would you like to accept?” That was the beginning of the end for my faith in Garmin’s FTP estimate :joy:

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Adding no value to your post but posting this anyway - I’ve never worked out how to get Garmin to estimate my FTP…it always shows “no value”.

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Fair point, but no ego here. I feel out of my element on this forum sometimes as a non-racer, and I just want a baseline to see improvement.

The trainer and my power meter are pretty spot-on during the ramp test and other workouts as well. If it was a power difference I imagine I would be seeing that all the time, not just in the final values.

I’ll reassess after the next test and see how much of it is me being bad at the ramp.

choose whichever is higher! :wink:

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I would try to use one power meter for all measurements. On TR you can use power match so it gets power from your power meter.

You may just put out more watts on the road. That is common for many people.

The other option is to do a 20 minute test and see what you come up with.

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Both Garmin and ramp tests are bad estimates of FTP but may be useful in tracking progress. If you want to know with accuracy what your FTP is, why not do Kolie Moore’s test?

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That is so weird, I only have a 530 and before that a 520. On longer tests like 20-min or 30-min or longer, the 520 and 530 were always within a watt or two of the other estimates. The ramp test has been the real wild card, its been mostly hit but enough misses that I don’t bother with it for FTP estimates.

The ramp, 8-min, and 20-min all have a range - for example if you are highly anaerobic and do the 20-min test then a lower multiplier something like .9 or .91 or .92 is likely more accurate than using .95 multiplier. Same is true for the ramp, although in my own experience the multiplier covers a much wider range and is therefore less reliable for FTP although ramp does give a good ceiling on 5-min vo2max power.

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Garmin’s estimated FTP used to be ballpark for me, but it’s been tanking week on week. Garmin will downgrade my FTP post-workout in spite of that workout being > IF 1.0.

My current FTP is likely somewhere in the range of 310-315w. Garmin thinks it’s 274w. I’m pretty sure I could ride 1hr @ > 274w and Garmin would either keep the FTP @ 274w or downgrade it.

I think I’ll just disable Garmin’s auto-updating FTP. I can’t see how it’s of any use.

Well since your best 20 avg during that ride would be 274 it would take 95% of that. If you want to use the garmin auto ftp feature you have to do max 20 min efforts to test it on the fly. Not that I’m suggesting that this is accurate either but its not going to track well if you aren’t doing the types of efforts it uses for its calculation

The auto FTP also works with your heart rate variation, if I remember right.

I’ve completed Kolie Moore Progression 3 FTP assessments i.e., >40mins @ FTP. Garmin doesn’t care and FTP remains ~40w lower than reality.

Yes because you didn’t do a 20 min max effort over FTP. What Is the Functional Threshold Power Feature on My Garmin Device? | Garmin Support

  • FTP Auto Calculation is enabled (refer to your owner’s manual)
  • Activity must include heart rate data from either a built-in optical heart rate sensor or from a chest strap
  • 95% of the average power for a 20-minute interval within the ride must be greater than the current FTP setting
  • The average power for that interval of time must be greater than the previous 20-minute power record.

i think it takes your initial VO2max estimate at the time of the FTP calculation from power data and assumes increases in estimated VO2max has a corresponding increase in FTP, there are some ways to calculated an estimated V02max from FTP or MAP but I don’t know the details here.

I have a Garmin 530 and premium HR strap.

Seeing good results from Garmin’s Auto FTP estimates. It works on efforts shorter and longer than 20-minutes.

Sometimes it takes a few days after a big effort before it updates the FTP. Below is a recent example of that. Prior to the data below Garmin had my estimated FTP at 249 (aligned but not same as WKO):

Date Workout Max 20-min Avg Power Garmin 530 FTP Estimate
May 7 17-min Climb 257W no update
May 12 group ride 232W 257W
May 17 3x8 @ 106% with 8-min rest between 219W 259W
May 19 group ride 212W 260W

WKO updated my FTP to 267 based on that 17-min climb, and since then has bounced around between 262-266. My coach reviewed 17-min climb and gave reasons for his estimate at 264. Garmin took 5 days before bumping to 257 and slowly moved it up over the next week.

As far as I’m concerned they are basically the same and range is 260 to 267). These are field estimates, and 10W difference is within margin of error IMHO.

AFAIK versus the 520, the 530 is using the updated Auto FTP algorithm based on VO2max estimation using Heart Rate Variability and Power:HR data.

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how has the V02max tracked with the FTP estimate? I have a 520 and it doesn’t seem to update with my V02max and only power

Garmin estimated VO2max has increased along with FTP estimate. Same in WKO. The difference is that WKO has more detailed estimates of absolute. For example 266 to 267W modeled FTP has absolute vo2max going from 3.990 to 4.003 L/min.

I’ve had the 530 long enough that I only vaguely recall the 520. I seem to recall the 520 needed those 20+ minute efforts to estimate FTP.

On the 530, I can bore you with more data showing it doesn’t need 20-min efforts.

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