FTP testing on a turbo

Hurricane151

I am contemplating getting a Powertap and calculating my FTP by completing a 1 hour test on the turbo.

My question is what effect does thevariable resistance of the turbo has on the test and results if any? Should it be set to a specific level?

Still to pull the trigger on a powertap as i'm not sure the benefits outweigh the cost and getting the threshold level correct id key to maximising the benefits of the unit.

Any ideas / advice welcome

napoleond

Testing on the turbo is pretty much the best way as you keep the variables to a minimum.
It doesn't matter what 'level' the turbo is set to as your power is what it is, that's the beauty of using a powermeter. I've had a powertap for 4 years now, fantastic bit of kit, espoecially if like me you are resigned to the turbo for most of your training.

Hurricane151

NapoleonD wrote:

Testing on the turbo is pretty much the best way as you keep the variables to a minimum.
It doesn't matter what 'level' the turbo is set to as your power is what it is, that's the beauty of using a powermeter. I've had a powertap for 4 years now, fantastic bit of kit, espoecially if like me you are resigned to the turbo for most of your training.

With that in mind I have the option of the Elite+ or a Pro+. Do you have any recommendations or experience with this level of unit? I would be using it with my Garmin rather than their own computer

SBezza

I would still do a 20 min warm up and then a calibration of the turbo if it allows you to do a calibration. The resistance may still vary slightly, and hence wheel speed might change around, but the powertap figure should still be accurate.

One thing to think about is that a 1 hour full out effort on the turbo might not be the best 1 hour effort you can produce, power might be lower on the turbo, and pacing for the full hour might not be optimal. Alot of us will do a 20 min test and from there you can guessimate roughly what your FTP might be, and this should be good enough to set training zones. It might not be the most accurate way, but then again the full hour on the turbo might not be the best way either. I only take my FTP from races that are around the hour mark, as I know I would struggle mentally to do that sort of power for an hour on a turbo.

SBezza

Hurricane151 wrote:

NapoleonD wrote:

Testing on the turbo is pretty much the best way as you keep the variables to a minimum.
It doesn't matter what 'level' the turbo is set to as your power is what it is, that's the beauty of using a powermeter. I've had a powertap for 4 years now, fantastic bit of kit, espoecially if like me you are resigned to the turbo for most of your training.

With that in mind I have the option of the Elite+ or a Pro+. Do you have any recommendations or experience with this level of unit? I would be using it with my Garmin rather than their own computer

As a training wheel the Elite + is more the adequate, I have one built on an Open Pro, and I use it for TT's with wheel covers on. If you really want to say a tiny bit of weight go for the Pro+ but most of the internals are the same.

Slack

Wow, 1 hour FTP test on a turbo trainer - good luck with that! 20 minutes sounds more likely as a starting point.

danowat

Slack wrote:

Wow, 1 hour FTP test on a turbo trainer - good luck with that! 20 minutes sounds more likely as a starting point.

+1, P.E. (for me at least) is so much more on a turbo for the same power, I could just about stick 20mins full chat, not sure about 1hr.....

Hurricane151

So how do you calc ftp from a 20min test? I thought ftp was average sustainable power over 60 mins

danowat

Ballpark is 95% of CP20 is FTP, some people are less, others more, it's about right for me (CP20 is 315w, therefore FTP is circa 300w (it's actually measured at 298w, but its close enough)

napoleond

I do mine as a 20 minute test for the reasons above. I have the 2012 Pro powertap, the only one I would avoid is the SL/SL+, I had one and had numerous problems, as did many other owners. The elite+ should be fine.

For FTP from 20 min test you would use 95% e.g. if the result is 300w then use 285 as your FTP (although I'd personally round it down to 280).

t.m.h.n.e.t

Hurricane151 wrote:

So how do you calc ftp from a 20min test? I thought ftp was average sustainable power over 60 mins

The test period is 20mins x 0.95 or 0.90. Industry standard IIRC

Alex_Simmons/RST

Hurricane151 wrote:

So how do you calc ftp from a 20min test? I thought ftp was average sustainable power over 60 mins

It is (well approximately 1-hour), and you can't, you can only make an estimate from 20-min power.

People here are quoting a value of FTP = 95% of 20-min mean maximal power*, however that's pretty unusual for most people, whose FTP is typically somewhat lower than that. 89-94% would be a more typical range. Where in that range depends on several things.

You can however improve the estimate by also doing an all out 5-min test in the same week. With both of those tests, the data can be used to ascertain your critical power, which is a very good proxy for FTP.

Of course you can just do the hour, it's great training, and you'll learn from the experience. You may not execute perfectly, but that does not matter, you get better the more you do such efforts.

Also, as another has mentioned, you may also discover a difference in the power you can sustain on the trainer to that which you are capable of outdoors. Time will tell on that. It's not uncommon for the difference to be up to 10%.

Finally, whatever number you settle on, it will be self correcting in any case once you start doing any form of consistent longer interval work. If the number is too high, you'll struggle to complete your intervals. So drop it down a bit. If they end up not being all that hard, it might be time to lift it a bit.


* the 95% figure is that suggested by Hunter Allen in the book "Training and Racing with a Power Meter", however keep in mind that the test protocol Hunter suggests also involves a hard 5-min blowout effort immediately before the 20-min test. Nevertheless, extrapolating from this 20-min test to an FTP value is still prone to an error range. It was intended to be a starting point, from which you then adjust as needed.

Herbsman

Is it best to find a long flat road to keep going up and down? I don't know any roads long/flat enough to do an FTP test but can book a closed circuit for an hour. The only problem is it has 2 hairpins so I would have to stop pedaling twice every 90 secs or so...

danowat

Herbsman wrote:

Is it best to find a long flat road to keep going up and down? I don't know any roads long/flat enough to do an FTP test but can book a closed circuit for an hour. The only problem is it has 2 hairpins so I would have to stop pedaling twice every 90 secs or so...

Local 25 mile TT course could be a good option, generally flat (as possible) with minimal amounts of slowing down needed

mclarent

Alex_Simmons/RST wrote:

Hurricane151 wrote:

So how do you calc ftp from a 20min test? I thought ftp was average sustainable power over 60 mins

It is (well approximately 1-hour), and you can't, you can only make an estimate from 20-min power.

People here are quoting a value of FTP = 95% of 20-min mean maximal power*, however that's pretty unusual for most people, whose FTP is typically somewhat lower than that. 89-94% would be a more typical range. Where in that range depends on several things.

You can however improve the estimate by also doing an all out 5-min test in the same week. With both of those tests, the data can be used to ascertain your critical power, which is a very good proxy for FTP.

Of course you can just do the hour, it's great training, and you'll learn from the experience. You may not execute perfectly, but that does not matter, you get better the more you do such efforts.

Also, as another has mentioned, you may also discover a difference in the power you can sustain on the trainer to that which you are capable of outdoors. Time will tell on that. It's not uncommon for the difference to be up to 10%.

Finally, whatever number you settle on, it will be self correcting in any case once you start doing any form of consistent longer interval work. If the number is too high, you'll struggle to complete your intervals. So drop it down a bit. If they end up not being all that hard, it might be time to lift it a bit.


* the 95% figure is that suggested by Hunter Allen in the book "Training and Racing with a Power Meter", however keep in mind that the test protocol Hunter suggests also involves a hard 5-min blowout effort immediately before the 20-min test. Nevertheless, extrapolating from this 20-min test to an FTP value is still prone to an error range. It was intended to be a starting point, from which you then adjust as needed.

Nice post, that should be stickied.

Alex_Simmons/RST

mclarent wrote:

Nice post, that should be stickied.

These blog posts should assist with future similar questions:
Testing FTP (the seven deadly sins)
Common mistakes in testing/setting FTP (sins of sins)
Indoor-Outdoor power differences (turbocharged training)

dw300

If you haven't held it for an hour, then it's not really your FTP .. 1hr FTP Test

Seriously though .. don't do it, you'll feel violated afterwards .. the 20min test figure turned out to be almost spot on.

okgo

Reckon unless you have some serious cooling that an hour at full gas would mean I'd overheat. I've been doing it in my garden topless with just bike shorts on in 3 deg and I'm steaming like a kettle and after 20 mins I'm very warm. Also breaking rhythm to drink is irritating.