Garmin 530 Estimated FTP vs TR Ramp Test

Just did the TR ramp test. It estimated a result of 248 and then - for the same effort - my Garmin 530 “detected a new FTP” of 257. First time to do a ramp test and I was predicting something close to 260…but perhaps I’ve been a little too festive over Christmas! Any thoughts on what causes the difference and which result I should use for TR?

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FWIW my Garmin 530 estimates of FTP have been fairly accurate, within 10W or so. IIRC the Firstbeat white paper shows the estimate uses machine learning algorithms on heart rate variability data, along heart rate vs power, and VO2max estimates.

My last (long) field test put my FTP at 264, and right now my power/HR data is the same while training and two days ago my 530 estimated 260 after an hour tempo workout. The TR ramp test tends to underestimate my FTP (likely because my FTP is usually at a high % of 5-min power at VO2max).

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Unless you are an anal retentive with the drivetrain upkeep you can expect to lose 8-10 watts to chain/drivetrain friction.

I guess that depends on where his PM is reading.

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Definitely. Speaking for myself, nearly all my power data is coming from crank on a single bike. Same bike, same power source, both inside and outside.

Just so it’s clear. You’re using the same power source for TR and Garmin?

@The-Lords-Donkey Garmin FTP estimate is really quite different from TR Ramp Test FTP estimate…so I’m not surprised there is some difference. This topic has been discussed on the forum before so you can use the search feature to get a more complete answer. Here is some info ‘straight from the horse’s mouth’ regarding Garmin FTP estimation:

https://www.firstbeatanalytics.com/en/features/functional-threshold-power-ftp/

" How Does It Work?

To calculate your FTP, the Firstbeat Analytics engine requires a stable VO2max estimate and enough quality heartbeat data recorded across a range of different intensities from low to high. Because external workload is a factor in the calculation, you will also need to ensure your bike’s power meter is connected to your device. Data can be gathered during a guided test specifically designed to record the data needed to detect your FTP, or it can be calculated from normal running activities that include enough quality heartbeat data from each zone.

Once this data is obtained, the Firstbeat Analytics engine identifies your FTP level by isolating the deflections in your heart rate variability that correlate to key indications of how your respiration patterns respond to the intensity of your activity.

Because HRV data is needed for this feature, use of a chest-strap heart rate monitor is required."

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Thanks everyone. I did read the previous posts and understand that the calculations are different. In the past I’ve used the typical all out 20min test. But it is pretty brutal. I guess I wonder why my Garmin estimate would run almost 10 watts higher than the ramp estimate and what to make of it. Should I see how I cope with the training plan using the higher (Garmin) number and adjust if necessary?

On Garmin it all starts with this AFAIK:

Source: What Is VO2 Max Estimate and How Does It Work? | Garmin Support

Worked for me for years.

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Yes, both tests were at the same time and both using my Garmin Vector pedals

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Think of it this way. Your ftp is around 250W. A good power meter is +/- 1%. Day to variation is maybe another 1%. I’ll do the additive and make it +/- 2% because we are rough estimating. So that is +/- 5W for a range of 245W to 255W. In other words, don’t think precision, think of a range that can fluctuate based on how you feel.

All that is assuming your Garmin 530 has enough good HR data to feed its ML algorithms. And you do enough 20+ minute efforts above 70% HRmax. And your HRmax and athlete level are set correctly. Some of that is dependent on your HRM and your body. I’ve done all the prerequisites starting back in 2016 and it works for me with a Garmin dual ANT+/Bluetooth chest strap. Your mileage may vary.

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I seem to have quite a wild variation and not sure what to do.

I record everything to 530 and wear H10 HRM.

Recent TR Ramp 258W
Recent Garmin FTP estimate 242W
Strava estimate (last 6 weeks) 234W

Failed 4x7min TR Threshold workout a few days ago with 254W new setting (I lowered from 258).

I’m thinking of doing the 530’s on board FTP test, has anyone else tried it?

I just wanted to chime in to say that I use a 530, but I mostly use Xert for training. With that, I think what Garmin are doing is really cool, even if it’s imperfect now. The more than can correlate HR and potentially other markers with power, it would seem you get closer to that holy grail of getting pretty good FTP estimates from just about any training data.

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I think you should! I’m thinking about doing the Garmin test as well…not because I need an accurate FTP number but just out of curiosity. Looks like the whole test would only take less than a half hour?

Asked some teammies and the word is you can take the whole test and the result might be ‘can’t calculate FTP’ or something like that. There is a colloquial belief that you shouldn’t drink or talk during the test.

I think FirstBeat is just looking for an inflection point in some HRV metric (change in sign of 2nd derivative). I don’t know enough about HRV to say if that is valid or not but there are a lot of interesting papers out there if you’re so inclined. Either way, it would be interesting to see where the garmin test falls on the spectrum of MLSS/75% MAP/VT2/Critical Power. Just out of curiousity.

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Could you try find out more about the Test and report back please?

Here’s something interesting… I changed my TR and Garmin setting to 242, did the workout below, and Garmin updated me downwards to 234W.

I dunno what to think! :rofl:

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I haven’t changed my FTP setting (264) since May 2021, did this short 75-85% tempo target workout on Friday 31 December:

and got this:

as I was walking up the driveway. Looking at power-to-HR data over 5 years, that ftp estimate is pretty accurate.

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My Garmin updates at random times, but usually when I do a ramp test. It is always a couple percentage beow the ramp test number, but close enough that training with either number I think would work fine. Last time I had a Garmin FTP 3 watts below the Intervals.icu estimate, which was about 3 watts below my ramp test a week before.

I did have an update pop up after a hard workout last week that put my 3 watts over the ramp number, but I am scheduled for a test next week.

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So in summary, what I’m hearing from the group is that both the ramp test and Garmin estimates are valid, but they each have different calculations…so expect discrepancies…for now, I think I’ll go with the Garmin figure of 257 and see how I do with the TR workouts…will be interesting to notice if it makes any additional recommendations and how I perform on the next ramp test…thanks everyone!

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I tend to ignore Garmin, FWIW. It’s constantly putting out FTP updates. Unless I know I’m doing maximal, I ignore it. FWIW, it seems more “accurate” when doing short max efforts, IME.

Anyhow, a 20W range seems about right.

Also, keep in mind, FTP estimates also varies day by day. Fatigue, etc. can affect what measurable metrics your body is putting out, in order to guesstimate…err…derive a number.

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This last Saturday I did an “anaerobic”workout, my Garmin estimated my FTP after the ride at 337. My ramp test FTP is 345. This was a hard workout but not all out, but you can see they estimated based off of normalized power for 12 minutes.( give or take)
I just wanted to share this example while it was still fresh on my mind from a recent workout and garmin estimation.

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