Which FTP

[LewisLondon]

So after getting a smart turbo, I though I’d try a mix of Zwift and Trainerroad, and now I’m confused!

I did a “one lap race” on Zwift, and managed to average 270watts over 14 minutes

This morning I did the full FTP test on TR (2 x 8 min efforts), and it subtracts 10% from your best effort. Best I managed was 250 for 8 mins, giving an FTP of 225.

The issue is if I apply the 10% rule to my Zwift ride, I get 243.

(And yes, I know neither of these are very high )

 

[amasidlover]

The 'truest' measure of FTP is a one hour steady ride leaving you utterly exhausted; however that's a thoroughly miserable experience and not something you're going to want to a) repeat the number of times necessary to get the level of effort perfect for one hour or b) repeat every few weeks to monitor whether your FTP is improving or not...

Most FTP protocols I've seen get you to warm up well (very well) and then go 'all out' for 20 minutes - then take 0.95 x the average power of that 20 minutes - some protocols specify 30 minutes 'all out' and then take the last 20 minutes to get a 'better' result.

Xert (Baron Biosystems) have a plugin that claims to give you an FTP estimate over much shorter intervals.

Personally my FTP hovered around 295-300W towards the later part of this season and that was from a variety of 20 minute efforts (including hilly and flat TTs) with various different warm-ups. The Xert plugin was giving me around 304-305W from about 7-8 minute (or longer) efforts. And in a one hour race on Zwift I came back with an average power of 287W - but that was not a steady effort at all...

Without wanting to go all 'TheSufferfest' about it, FTP is a pretty crude measure and any test shorter than hour is only ever going to be an estimate - the key question is what are you training for?

My power profile (measured by looking at my best efforts for 5 sec, 1 min, 5 min, 20 min and 1 hour over a 4 week period) shows I'm very strong from 5 mins upwards but a terrible sprinter

If you're doing a variety of racing (TTs, crits, hill climbs) then you need to be training across the spectrum of interval times, if you're focusing on 25 mile TT's then there is little point in doing training that will improve your 5 minute power.

If you're looking for just general improvements for riding then I'd pick a test protocol you feel you can do regularly and do that every few weeks.

 

[T.M.H.N.E.T]

For 18w I'd just go off the higher one.

 

[Hacienda71]

If you did your race one day and then did your FTP the next you won't have given your body sufficient time to recover and so you figures will be out. You want a period of rest before a test.

 

[Racing roadkill]

4DP from sufferfest is where it’s at now.

https://www.google.co.uk/amp/s/www....ith-the-sufferfests-new-4dp-platform.html/amp

 

[MrPie]

Chances are you'll get a higher number on an outdoor run. Make sure you are recovered. Warm up. 20 mins full gas on a clear stretch of quiet flattish road * 0.95. Job jobbed. Bet you a pint you boss 285w

 

[amasidlover]

Round here there aren't many places to do 20 mins full gas on a clear stretch of quiet flattish road; although I'm guessing it maybe easier in Aberdeenshire

 

[Tin Pot]

So after getting a smart turbo, I though I’d try a mix of Zwift and Trainerroad, and now I’m confused!

I did a “one lap race” on Zwift, and managed to average 270watts over 14 minutes

This morning I did the full FTP test on TR (2 x 8 min efforts), and it subtracts 10% from your best effort. Best I managed was 250 for 8 mins, giving an FTP of 225.

The issue is if I apply the 10% rule to my Zwift ride, I get 243.

(And yes, I know neither of these are very high )

It’s not like me to be controversial (pauses for laughter) but I’m in disagreement with almost all of the previous posters.

1. You don’t know your “true” FTP

All power meters produce variable results, +\-5% on the good ones which alone can account for a 10% variation.

All apps calculate FTP differently, and in different test protocols.

2. You don’t need to know your “true” FTP

Your TrainerRoad training plan is built upon the results of the TR test - use that in you TR training.

Similarly, use your Zwift result in Zwift only.

HTH

 

[400bhp]

Everyone replying so far has said useful stuff.

I'll add a couple of additional points.
- Your FTP will change day by day anyway. It's not fixed
- The "average" in Zwift may or may not be a time weighted average. It may be some kind of weighted average which may give an inflated number comparing to TR's time weighted (or straight) average

This article by Chris Carmichael is worth a read:
https://trainright.com/cts-field-test-why-eight-minutes-not-20/

 

[CXRAndy]

Zwift is a little generous with its FTP. I'd take the TR FTP as the realistic number. Now take the Zwift number and train around that number on TR. FTP is only a figure, training and racing are different

 

[jiberjaber]

Take the TR number as it is following an actual method that you can repeat to provide some consistency in measurement.
Next time you measure, use the same method.
If you are doing some workouts which are supposed to be hard, then either your FTP was a bit low when you measured it or you've improved. Either way on the likes of Trainer Road you can up the FTP level a bit till you get to something that feels challenging... though note some workouts might be in a zone which isn't supposed to feel challenging!

Test again in a few weeks time, try to ensure some consistency in your approach to testing (to remove any variables) so suitably rested and fuelled before each test is a good approach.

I wouldn't worry about "neither of these are very high" it's just a number that's particular to you, you can't compare it with others really, its a reference point to set training zones for you, so approach it like that and as you get fitter, it should increase. (though note that the reverse is also true of as you get less fit, it might go down).

Duration of the test is often debated, 20min is more an exercise in pacing than the 8min and at least with the 8min if you get the pacing wrong on the first effort, you know what to do to correct it on the second effort... On a 20min effort if you pace wrongly (blow up by going to hard, or under read due to not going hard enough) then its a couple of days before you can test again.There are some schools of thought about 8 v 20min and the result relative to some types of training specificity so one length might be better if you are focused on sprint training rather than climbing training for example...

The key thing is use the same test each time and replicate approach so you can get a figure you have some trust in

It's also true that your indoor will be likely lower than your outdoor FTP for a whole load of physiological and psychological reasons - but if your structured training is all based on the turbo then there is no point in worrying about your outdoor FTP as if you set your indoor workouts based around that you will be in a new level of pain cave experience!