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Andy

Calculating FTP

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Ok so recently got my first power meter. Did  a 20min FTP test, and after the calculations came in at 254. My initial thought was that this was low (maybe I watch too many YouTube hero’s bragging about their FTP’s) as I have rode 4:55hr IM bikes 3 times and would consider myself in solid bike fitness shape when I did the test.

Anyway my question is, I did the test on my indoor trainer and went flat out - HR was maxed out cadence around 90rpm and I faded a bit in  the last 5min. The other day I was riding outside on a flat road into a head wind and was easily holding 350 watts with a cadence around 75-80. I maintained this for around 12min before turning and picking up a tail wind. Before turning I wasn’t struggling and felt I could easily hold it for the 20min.  So which way should the test be done? With both these scenarios FTP result would change by about 80 watts.  I find my current FTP of 254 works well on the trainer and produces hard workouts, whereas riding outdoors sessions are a lot more comfortable at the same wattage efforts.

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This is either the best piss take or your power meter needs calibration.  

Do you race a grade crits and road races?

upload your data here  

 

Edited by Peter

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1 minute ago, Peter said:

This is either the best piss take or your power meter needs calibration.  

Do you race a grade crits and road races?

upload your data here  

 

I think its AP again...

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19 minutes ago, Andy said:

Ok so recently got my first power meter. Did  a 20min FTP test, and after the calculations came in at 254. My initial thought was that this was low (maybe I watch too many YouTube hero’s bragging about their FTP’s) as I have rode 4:55hr IM bikes 3 times and would consider myself in solid bike fitness shape when I did the test.

Whether its good or bad kinda depends on what you weight. Whats watts/kg are you pushing?

The other scenarios you're talking about are not the same as the first do difficult to say which is the correct one

Try again on your trainer, or go get professionally tested.

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1. What sort of power meter?

2. Is it calibrated and are you checking torque zero?

3. What are you using to inspect the data?

4. There can be a difference between power you can sustain on an indoor trainer and outdoor riding. What sort of trainer? Do you have sufficiently effective cooling?

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38 minutes ago, Prince said:

I think its AP again...

New account number 82. Haha. 

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3 hours ago, Andy said:

. The other day I was riding outside on a flat road into a head wind and was easily holding 350 watts with a cadence around 75-80. I maintained this for around 12min before turning and picking up a tail wind. Before turning I wasn’t struggling and felt I could easily hold it for the 20min.  

Ya power meter gone done got broke. Are you sure you are reading the power and not time of day, could be 3.50? Post on Slowtwitch for additional advice and report back.

Edited by zed

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Hi Andy,

Don't worry about the knobs on here. I am exactly the same. My power is significantly lower on the trainer than on the road and i can hold a much higher power when climbing or riding into a headwind. I don't know why it is but i don't normally train to power on the road, only the trainer. 

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A) your power on the trainer is probably lower than on the road (as is mine)

B )  You say you 'faded a bit'. how much is a bit because FTP test is supposed to be relatively stable power so you might have overcooked the first bit and bombed at the end. I think executing a FTP test correctly can take 3-4 times to get right in terms of pacing it for the full time period.

C) I can ride 20 mins uphill at higher than 95% FTP but I still wouldnt use that number as my FTP. It might be, i dunno, but I wouldnt use it

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23 minutes ago, 2bruisedplums said:

Hi Andy,

Don't worry about the knobs on here. I am exactly the same. My power is significantly lower on the trainer than on the road and i can hold a much higher power when climbing or riding into a headwind. I don't know why it is but i don't normally train to power on the road, only the trainer. 

2 posts in and he writes:


"The other day I was riding outside on a flat road into a head wind and was easily holding 350 watts with a cadence around 75-80. I maintained this for around 12min before turning and picking up a tail wind. Before turning I wasn’t struggling and felt I could easily hold it for the 20min."

Suggesting he could manage 400w+  for an FTP test if he can manage 350w comfortably for 12mins. Note Alistair Brownlee's FTP is 400w. Perhaps he should have entertained the idea his PM wasn't calibrated correctly, that's what most people would do if they started putting out wattage pro triathletes would be proud of....

 

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29 minutes ago, 2bruisedplums said:

Hi Andy,

Don't worry about the knobs on here. I am exactly the same. My power is significantly lower on the trainer than on the road and i can hold a much higher power when climbing or riding into a headwind. I don't know why it is but i don't normally train to power on the road, only the trainer. 

Yeah but what's your HR doing.... You might be pushing 300w up a hill, but your HR isn't going to be the same as 200w on the wind trainer. Your power output shouldn't differ much from trainer to out on the road.

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Also saying how fast you ride an ironman without mentioning the run is a bit misleading. If you can run well off that time and you weigh between 70-80kg your FTP is in the low 300s, maybe even high 200s and most definitely nowhere near 350. 

Edited by Rog

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Experienced he same results myself and also with athletes I coach.  My indoor wattage is way below what I can hold on the road and I can hold higher wattage again up a long climb.

For indoor sessions I use the FTP I can set on the Indoor trainer. For climbs I pace myself based on power I have sustained up previous climbs. I usually gauge my Triathlon goal wattage based on a FTP test performed on a Velodrome riding my Triathlon bike (using the same power meter I race with).

Remember that the algorithms provide an estimation of FTP, not an exact result.  Also your ability to hold a certain percentage of FTP over a particular distance is also an estimation (that will vary from athlete to athlete). Treat it as a starting point for working out what you can sustain over different distances.  I also look at my heart rate, because weather conditions can also affect what wattage you hold.

 

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4 minutes ago, Prince said:

something fishy about this whole post....

image.jpeg.c9961b83819e00fd4b8539ba43664f4c.jpeg

 

  • Haha 1

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17 minutes ago, Prince said:

its just that ANDY, is very quiet...

Calibrating his PM?

  • Haha 1

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Wow, now I know why I don’t bother to post anything.  To answer some of your comments - I  try to remember to calibrate power meter before every ride. Did I on this one? Can’t remember but probably.  When doing the FTP test, for sure I didn’t pace it right as I went out too hard. It was my first attempt.  Ave power would have dropped by 30w in last 5min. I have always ridden with a low cadence in training and racing of around 70-75. I did the test at 90 cadence as that’s what I read you should do it at.  I run around a 3:30-3:40 IM run off a 4:55 bike at 77kg. Is that good? No idea. Is that relevant? I only put that in to give some background into what I can ride (course dependant) in comparison to what my FTP test came back at to see if it was low or not. The question I was trying to get across was how to get an accurate ftp figure when riding outside you see big differences in perceived effort and heart rate for the same power output that you do on a trainer.

Edited by Andy

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1 minute ago, Andy said:

The question I was trying to get across was how to get an accurate ftp figure when riding outside you see big differences in perceived effort and heart rate for the same power output that you do on a trainer.

Can't tell you how accurate or inaccurate it would be but I presume it would be less accurate than a trainer with power (properly calibrated of course). Too many variables outside that change all the time - eg. temperature, wind, etc etc

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in the past i have done separate tests for inside vs outside training, done separate tests for the difference between stages PM and SRM but it does get pretty tricky, especially if you are trying to monitor it all somewhere like Training Peaks (cos I think it only lets you set one FTP).

Now I have one FTP that i performed on the trainer and on my SRM which is where i do most of my intervals. My stages is on my road bike is only used for commuting usually so if the TSS is off a bit, so be it..

I would probably try another test if i was you and try and pace it more evenly as I think, that fade at the end would be an issue

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32 minutes ago, dazmuzza said:

Too many variables outside that change all the time - eg. temperature, wind, etc etc

The same variables that occur in a race.

If you don't learn how they affect you (or how to overcome them), how are you going to adjust for them in a race.

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39 minutes ago, Andy said:

I have always ridden with a low cadence in training and racing of around 70-75. I did the test at 90 cadence as that’s what I read you should do it at.

If you have rarely ridden at 90rpm, it is no surprise that you started to fade after 15 mins.

If I'm cruising in a group ride, I will ride around 75rpm.  During efforts or Sprint Triathlons I will ride at 100rpm.  Olympic Distance or longer efforts my cadence will drop to 95 and in a Half Ironman it will be closer to 90rpm.  If I raced Ironman, it would be probably be mid to low 80's (but I would need to do more training at this level).

When applying effort, different cadences will activate different muscle fibres.  Higher cadence uses slow twitch muscles that use less energy and have far more endurance, but your heart rate will be a little higher.  Lower cadence means more torque which activate the fast twitch fibres, meaning more available power, but less efficient and far less endurance.  Of course in an Ironman, the wattage is typically so low (especially for the pro women), that the torque levels are unlikely to activate the fast twitch fibres.  So the low cadence (with lowish torque) still uses mostly slow twitch fibres while keeping the heart rate down.

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49 minutes ago, Rob said:

The same variables that occur in a race.

If you don't learn how they affect you (or how to overcome them), how are you going to adjust for them in a race.

Yeah I know but the question is about calculating accurate FTP - not how to adjust FTP for race conditions. 

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Have a go at a ramp test, it will eliminate the pacing effort in your first 20 min FTP test. While the tests are structured differently it would be interesting to see how the numbers compare.

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1 hour ago, Andy said:

Wow, now I know why I don’t bother to post anything.  To answer some of your comments - I  try to remember to calibrate power meter before every ride. Did I on this one? Can’t remember but probably.  When doing the FTP test, for sure I didn’t pace it right as I went out too hard. It was my first attempt.  Ave power would have dropped by 30w in last 5min. I have always ridden with a low cadence in training and racing of around 70-75. I did the test at 90 cadence as that’s what I read you should do it at.  I run around a 3:30-3:40 IM run off a 4:55 bike at 77kg. Is that good? No idea. Is that relevant? I only put that in to give some background into what I can ride (course dependant) in comparison to what my FTP test came back at to see if it was low or not. The question I was trying to get across was how to get an accurate ftp figure when riding outside you see big differences in perceived effort and heart rate for the same power output that you do on a trainer.

It's all good, we're just pulling the piss. You should be glad you posted here and not slowtwitch.

Rightly or wrongly I do my FTP test on my WT, not outside, less variables to contend with and your "test environment" can be easily replicated. 

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1 hour ago, Andy said:

 I run around a 3:30-3:40 IM run off a 4:55 bike at 77kg. Is that good? No idea.

I thought anyone would have a good idea doing these times,

FM

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24 minutes ago, dazmuzza said:

Yeah I know but the question is about calculating accurate FTP - not how to adjust FTP for race conditions. 

I'm never expecting my FTP to accurate.  More of a ball park figure within 5 watts.  You get better at performing FTP tests over time, but there will always be variables other than weather conditions that affect the result.

For me, I don't find wind (discounting gale force, or particular nasty crosswinds) has a big affect on my power output.  Whereas temperature does affect me - maybe why my numbers are so low indoors due to feeling so much hotter.

I can judge improvements (or decline) looking at my training data for sustained efforts.  Strava is good for comparing efforts up climbs.  So I typically have a pretty good idea of my FTP before I do the test.

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2 hours ago, Andy said:

I run around a 3:30-3:40 IM run off a 4:55 bike at 77kg. Is that good? No idea. Is that relevant?

LOL

That puts you in the top 40 overall at most Ironman's  (I looked at Port and NZ)

You don't need a powermeter. 

BTW I still think this is the Ass Puppet 

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I'd be tempted to work with two numbers if they end up markedly different. If you were to base your metrics solely on the indoor trainer, and then race to those parameters you could come undone, so for the real race prep stuff I'd be tempted to set yourself an ftp and race-specific zones etc on your race bike outdoors.

Oh, and I'd also not get too hung up on power (don't shoot me people!) as they can and will go wrong. Two of my four IM races the power meter shat itself for some unknown reason after long haul flights, so really important to be able to race by feel too if you need to (I dare say at 4:55 bike you must know what you're doing!)

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21 hours ago, zed said:

Your power output shouldn't differ much from trainer to out on the road.

There are many factors in play when considering the power one can sustain on a trainer compared with out on the road. In some cases it will be similar, some people can actually sustain more on a trainer while most experience their outdoor power to be higher than on a trainer by handful of percent.

It can also be quite a large difference. I know for instance on a crappy old magnetic resistance trainer I once had I was at least 15% down on my outdoor power. It was horrible to use. When I upgraded to a custom made trainer with a massive flywheel and double reduction gearing, the gap between my indoor and outdoor power narrowed quite a bit and the last 20W (at threshold) I was able to close by getting a power industrial fan for cooling.

18 hours ago, dazmuzza said:

Can't tell you how accurate or inaccurate it would be but I presume it would be less accurate than a trainer with power (properly calibrated of course). Too many variables outside that change all the time - eg. temperature, wind, etc etc

Both trainers and power meters can be accurate or inaccurate. It depends on the trainer and the power meter and the user.

A quality power meter used correctly will be accurate in the face of variable conditions experienced outdoors. A quality power meter can also be woefully inaccurate on a trainer if not used correctly.

 

18 hours ago, Rob said:

When applying effort, different cadences will activate different muscle fibres.  Higher cadence uses slow twitch muscles that use less energy and have far more endurance, but your heart rate will be a little higher.  Lower cadence means more torque which activate the fast twitch fibres, meaning more available power, but less efficient and far less endurance.

The primary factor influencing muscle fibre type recruitment is power output. A modestly lower or higher cadence at similar power output isn't going to make much difference to fibre type recruitment.

Edited by Alex Simmons
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18 hours ago, Andy said:

I  try to remember to calibrate power meter before every ride. Did I on this one? Can’t remember but probably.

It's worth checking. What sort of power meter?

 

18 hours ago, Andy said:

When doing the FTP test, for sure I didn’t pace it right as I went out too hard. It was my first attempt.  Ave power would have dropped by 30w in last 5min. I have always ridden with a low cadence in training and racing of around 70-75.  I did the test at 90 cadence as that’s what I read you should do it at.

Pacing well takes a bit of practice, so just chalk it up as a learning experience and a nice bit of training.

One trick with such tests is not to think of them as taking precisely 20-min, rather start out conservatively with power/effort, and then gradually increase it as you feel you can. It will take several (3-5) minutes of riding before you can begin to really make that judgement as perception of effort take a while to catch up with reality.

So say after 5-min then again at 10 and 15 minutes, gauge how you are feeling and whether you can pick it up a bit more, or not as the case may be.

If you find that as you approach 20-min you are riding a significantly higher power than you did in the first 5-min, then just go longer, add 3, 4, or 5 minutes to the end of the effort at the higher power and simply use the best 20-min power as your result.

Threshold will be roughly that best 20-min less about 7% give or take a few%. You can narrow it down a bit more by adding a mean maximal effort of ~4-6 minutes on another day. Those two efforts can be combined with a simple model to come up with a better estimate of FTP than say using "95% of 20-min test".

Forget about cadence and just ride they way you feel you can get the power down for the effort.

 

18 hours ago, Andy said:

I run around a 3:30-3:40 IM run off a 4:55 bike at 77kg. Is that good? No idea. Is that relevant?

No, it's not relevant to the questions you ask.

It's only relevant in the context of those seeking to validate quoted power numbers. Power numbers quoted at the higher end tend to elicit more suspicion from a jaded online public, because unfortunately experience in the online world suggests there are a fair share of those quoting vanity/fantasy/unrealistic power numbers. Often however it's just because the person is not experienced with such things and they don't know if a number is valid or not for them. It might just indicate a problem with the measurement process or the device, and of course it's also entirely feasible these numbers represent reality.

 

18 hours ago, Andy said:

The question I was trying to get across was how to get an accurate ftp figure when riding outside you see big differences in perceived effort and heart rate for the same power output that you do on a trainer.

As I said in another response above, there are many factors in play that can see indoor and outdoor power differ, aside from validating any differences in the actual power measurements themselves. I wrote this piece 10 years ago to go through some of those factors:

https://wattmatters.blog/home/2009/01/turbocharged-training.html

Hope that helps.

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On 03/10/2019 at 6:57 PM, Andy said:

 

Anyway my question is, I did the test on my indoor trainer and went flat out - HR was maxed out cadence around 90rpm and I faded a bit in  the last 5min. 

Alex will be more across this than I am but I often find 20-30W lower indoors unless there is very very good airflow (e.g. from an industrial fan or two)

On 03/10/2019 at 7:55 PM, Peter said:

New account number 82. Haha. 

Coming from you! 😂😂

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26 minutes ago, Aidan said:

 

Coming from you! 😂😂

I 100% honestly only have 2 accounts.  

One of which I don’t even know the password its been So long. 

Admins can compare ip addresses. 

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39 minutes ago, Peter said:

 

Admins can compare ip addresses. 

You'd be surprised who have accounts here and log on regularly. 

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1 hour ago, willie said:

You'd be surprised who have accounts here and log on regularly. 

I wouldn't be surprised at all.

I'm still waiting for TA to buy you out and close it down.

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Just on the FTP thing, if the number is higher from outdoor riding, that will be your FTP. That you can't sustain as high a power output indoors doesn't mean your FTP is lower, rather the conditions are such that you are unable to fully express your aerobic capability. Same with impacts of altitude, heat etc.

What to do about it?
i. do the things I mention in my blog item to see if the gap between power output inside and out can be narrowed, and/or

ii. training should always be relative to what you can do. Using a proportion of FTP to set a training level really is just a starting guide. If you know that you are 20W lower on a trainer, well you should expect to adjust power levels for trainer work accordingly.

Pithy Power Proverb: "Alls you can do is alls you can do."

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I had written a few words and nearly went to post, then saw the second thread and found people had already answered.

As Alex has basically said everything (and more) that I would have said, the only thing to add is maybe look at doing a ramp test as well, which may give a different answer, and make sure you have adequate cooling.

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