Power Comparison (Indoors to Outdoors) with P1 Pedals

[Splash]

Hello all.


Consider this scenario - P1 pedal use on TACX NEO Trainer:

If the same power is measured on the P1 pedals and the inbuilt TACX NEO power meter (or within a few Watts of each other), does this imply that I can use this indoor measured FTP (and hence zones) for outdoor use on my dedicated outdoor bike with these same P1 pedals, so that training levels and data is consistent?

If not, how do utilise the same FTP for both indoor and outdoor training?

What would an accepted difference in watts between P1 pedals and TACX NEO watts (if any)?



Splash

[deechee]

I hope you captured the data from both devices separately haha. Ant can broadcast to multiple devices.

I use the same numbers in and out and my Cp20 numbers are within 5-10 watts when I test. How did you determine your FTP? Training with a PM says to drop a 20min effort when your numbers fall 3-5% so I would think that range is acceptable for error margins most cases. Dcrainmaker talks a lot about acceptable margins if you read his PM reviews.

What is your concern? If you're trying to find an accurate baseline for a training program, I would take either number that motivates you. As you test yourself more, you'll get better at the test and understand what you need to work on. Remember it's just a test, you don't need to overthink it. The consistent training ; ability to repeat efforts at an intensity is what matters.

[ergott]

(or within a few Watts of each other)

Splash

That's the Kickr (see what I did there?)

A few watts can effect CTL and other long term training plan aspects. They would have to be very close in accuracy. How close are the results between power meter and Neo? Is is consistently close for all types of efforts?

[laupsi]

indoor power does not equal outdoor power

[Splash]

Thanks Gents.

Great points raised by all. I have not yet acquired the P1 pedals, but may in the future.

Given that indoor power does not equal outdoor power, my concerns revolve around the following:


Should I be using the indoor measured FTP to set training level zones, pacing and watt/kg when training outdoors on a bike fitted with a PM?

Should I be using the outdoor measured FTP to set training level zones, pacing and watt/kg when training indoors on the TAX NEO?

Should I be using an outdoor measured FTP when training outdoors and a separate indoor measured FTP when training indoors?

How do others integrate outdoor and indoor PM data under the single power profile analysis with different FTP/zone levels (e.g. - Strava, TR or TP)?

How do I ensure PM data consistency/integrity for post ride analysis if 2 separate FTP (zone levels) are used for a single rider profile (e.g. - Strava, TR or TP)?




Splash

[shovelhd]

If you are using an indoor training program like Zwift or Trainer Road, set it up to use the pedals as the power reference. Done. Your indoor power equals your outdoor power. No need for any more questions. It's that simple.

[ergott]

When I'm riding Zwift I use my crank power meter for numbers, not my smart trainer (Tacx Bushido).

When you get the numbers to be accurate then power indoors is the same as outdoors. Having the resistance vary with the terrain like outdoors really helps too. Then your not just slogging away at the same cadence/power all the time.

I just got off doing 2 reps up Zwift Watopia mtn. It's a great length/grade to work with.

[Splash]

Thanks Guys.

Those riders who use 2 separate FTP values (1 for indoor and 1 for outdoor), how do they incorporate these different values (and zone levels) into their post rise analysis?


Splash

[zank]

I used to just manually change the FTP for the ride in WKO.

[Tandem Rider]

I can't speak for others, but I don't. The indoor number is what it is and so is the outdoor number. I just do the intervals and be done with it.

Too much analysis is time wasted that could be used for another interval, which unlike analyzing every crank rev, really will make you faster. Do the test, calculate your numbers, get back to training. Repeat in 4-6 weeks.

[wallymann]

indoor power does not equal outdoor power

what does this mean? how would the time rate at which work is done differ whether on a trainer vs outdoors?

one's ability to *produce* power is different indoors vs. outdoors, but measured power *is* measured power regardless.

[Web1111a]

As someone whom is interested in learning about power for training why is there a difference in inside and outside power


Is this just the equipment questions of usIng the trainer versus the real power meter variance ?

Or is indoor training just not as intense?


Thanks

[Tandem Rider]

Same bike, same PM, same RPE, same HR, I will show lower watts indoors. My speculation is lack of airflow, shorter warm up, and absolutely detesting trainers.

[drewskey]

Same bike, same PM, same RPE, same HR, I will show lower watts indoors. My speculation is lack of airflow, shorter warm up, and absolutely detesting trainers.

I can boil mine down to improper airflow. I can hit the sustained training intervals outside, but bring me inside and I make it about 3/4 the way through before my HR shoots to the moon.

[Web1111a]

My experience last year was that I don't get my heart rate up as high and my mph are not as high indoors

I seem to have issue pushing myself indoors

[shovelhd]

I never changed my FTP indoors to outdoors. I simply derated my workout targets by 7% for indoors. Simple.

[laupsi]

I never changed my FTP indoors to outdoors. I simply derated my workout targets by 7% for indoors. Simple.

On the nose!

[benb]

I also have that issue where my indoor power seems to be lower due to my body overheating on the trainer causing my heart rate to skyrocket. Maybe if I got a ton of fans I could do it but my wife would probably object to that, even in the basement.

Not sure about the OPs Tacx. I have a Tacx flow (pretty old at this point but they still sell it and it looks exactly the same as mine) and the power #s that come out of it match my Stages PM pretty accurately as long as I don't relax one leg or something, but it also is a weird # because it looks like it's reporting a rolling 30 or even 60 second average power or something. It is much, much, much less responsive and variable compared to the on-bike PM. It might be 5w lower or something from losses but generally they're really close.

The flip side of all this is on the trainer there is way less variation than the road anyway as grades/resistances are less variable and you don't have things like shifting wind and cars and trucks disturbing your airflow. So who knows.

I use the # from outside and once on the trainer I can use the # of the Tacx or off my Garmin, no real difference. This winter will be the first I have both power meters available for the entire trainer season, and I picked up a lot of watts over the summer so we'll see if I have significant trouble hitting those #s on the trainer due to overheating. My FTP is about 35w higher than it was in the middle of last winter. If I was overheating at the lower value, I'm probably even more likely to overheat at the higher value.

[Tandem Rider]

Let's see here, Drewsky shortens up his workouts without changing his target. Shovel derates his target by 7%. And I just do an indoor test to get my indoor number. 3 people telling you basically the same thing. Pick whichever method you are the most comfortable with.:)