4DP vs Garmin FTP

Training
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As suggested by another follow sufferlandian on the facebook group, I’m bringing this to the forum.

Last saturday I did 4DP to get ready for Winter training but according to 4DP my FTP is 203W but according to my Garmin it’s 235W for the same ride (not far from my former FTP 236). Should I keep 4DP numbers or update them? or do half monty?

One of the main reasons I couldn’t hold the suggested power target is that I had eggs and beans for breakfast (don’t laugh) and start getting acid reflux after the 5 min test. Also had some pain on my right quad so I didn’t want to push it.

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2

I think you can find an answer in the following article:

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3

If your Garmin is reading the exact same power source as the SUF app then something looks wrong there. Did you get any warning with your FF results (e.g. best 20min not being from the FTP test section) or see power dropouts in your SUF log? For the best support I’d recommend you email the minions as they can see your data etc.

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Hey, just to confirm, you did the Full Frontal and also recorded your workout on your Garmin?
When you did it last time and got 236 was that on the Sufferfest or on the Garmin too?

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Yes, I have them both reading from my 4iiii powermeter and the results didn’t have any warning

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Yes, I had both recording using the same power source. The 236 was from last Half Monty I did back in April. I have been riding consistently this summer and managed at some point to hold 241W outdoor for more than 20 minutes.

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Thanks for the extra detail, it may have something to do with when you ride Full Frontal, your FTP is taken only from the 20minute section and your Garmin may be recording the number based on the whole workout?

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Rule of thumb in the old days was: never adjust downwards, unless you lost a leg the day before. You either didn’t try hard enough, violating TINT, or you were feeling the effects of wandering too close to Couchlandria.

Things were so much more less complicated back then :joy:

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Can you look at the actual data on the file? If you uploaded to strava from your garmin, try something like intervals.icu and see what’s going on. If the data looks good compared to what you see in the sufferfest app, then others are likely right that the garmin is applying it’s own algorithm to your workout.

Their algorithm might be using some form of normalized power, which could explain why the number is that much higher. Makes sense for a stochastic looking workout.

As an aside, if anyone uses strava, definitely check out intervals.icu (typed into your browser). I was just told about this by a friend and it’s pretty cool!

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