What's your wattage?

[TxDoc]

Actually the best way to determine your FTP is to do the FTP test, which by definition is a 1 hour time trial. So the golden rule would be - you want to know your FTP? Do a 1h time trial as hard as you can go and measure average power over the 60 minutes.

For some reason, a lot of people seem to not want to do the actual 1h TT, so they resort to other shorter tests like a 20' test, or a 30' test, and such. I think Coggan listed somewhere all the methods to calculate FTP and how each one is less accurate than the actual 1h TT.
Taking 95% of your 20' test average power will give you an approximation of your FTP, but keep in mind that some people test better than others at 20 minutes. In other words, if you really do your 60 min TT and your 20min TT, you may find out that your FTP is actually 97% of your 20min or maybe 92%, or 94%, or who knows. It lies usually between 92 and 98% - but when you talk time trial you talk seconds, so that 4 or 5% difference may be really significant.

Also be aware that what you see as 'average power' from a ride or CT training session is usually higher than your actual FTP.
This is especially true of road racers as opposed to time trial specialists. The old coaches when we were young used to say that if you spend more than 70% of your race pedaling, then you are doing something wrong. Meaning that you should coast, draft, sit in and rest for a good portion of your race, and be ready to attack full-speed when needed. So over 1h of race or ride time, you will spend some significant time resting, and then be able to produce a higher power output in the remaining time. If you had to pedal all the time, your power output would be lower.
The main reason is that FTP is your sustainable power at threshold, when you have to maintain that power output for the whole hour. On the other hand, when you are doing your road race, or your regular training sessions - you can alternate the surges with recovery periods where you sit in or draft or rest. So when you look at your graph, you will see spikes in wattage that show the surges, often leading to the anaerobic zones - and then recovery periods at low wattage when you rest or when a teammate is pulling you along on a race. At the end of the race (or workout), the average power may be higher than what you would be able to sustain on your own without rest and without breaks.
Makes sense?

Some people resort to normalized power to try and extrapolate an average number that represents what would have been your average power if you had a smooth ride sustaining the pace (instead of 'intervals' or 'surges'). Same as above (and for many of the same reasons), the normalized power often tends to be a higher number than your FTP would be, if you were to actually measure it by the 1h TT definition test.

It takes some time if you are not used to ride 'all out' for a while, but my suggestion would be to really do a FTP test if you want to determine FTP. Yes, it is painful, but then time trial is always painful, so there's not much of a choice - and at least it will give you believable numbers.

Last, there are a few issues with measuring wattage on computrainer as opposed to using a power meter on the road (srm, quarq, powertap, whatever), and this is due to the fact that the bike is anchored to a trainer, as aicabsolut mentioned earlier. MAP tests on computrainer do not work that well. Max power jumps work even worse. FTP however can be done on the computrainer, although it may give you a result that is slightly different than what you will see if testing on the road. It will most likely be in the 7-8% difference window, so if you can live with a small % error, it will work. If your goal is to race TT, then that error is too much, and I would forget the computrainer and use SRM or PT, much more reliable.

As per how to gauge your average power/weight at FTP when compared to other people, there's a table on WKO that does that automatically. You can also just look at the printed table on Training Peaks and find your FTP there to see where you stand: the article is at http://www.peaksware.com/articles/cy...profiling.aspx and the table at http://www.peaksware.com/media/69406...ofiling_v4.xls

Hope this helps, good luck

[aicabsolut]

Thanks for the explanation, TxDoc!

One problem I have with estimating my FTP other than the boredom factor for doing a 1 hr effort on the CT is that in general, my 20km TT is much better compared to my 40km TT. This is going by how I place relative to others, particularly in Merckx-style TTs. So, what does that mean for my FTP? That it really is pretty low but I probably follow more of a pursuiter power profile? (I haven't tested it, but I'd guess that to be the case). So, when doing FTP-based CT workouts (erg files programmed to put you at x % of FTP for each interval), should I continue to set my FTP on the high side considering that those workouts are relatively short?

One day, an SRM will be in the budget. One day.

[limewave]

Yes, thank you for the information!

My main goal is to improve my cycling. I'm not a time-trialist or road racer. I like to ride. I like to mountain bike. And my goal is to do 2-3 mountain bike races next year.

I'm going to try the 1 hour time trial on the computrainer. That sounds like my kind of suffer-fest (not that I'd want to do that every week ). I'll do the FTP test soon, again towards the end of January, and once again in March. I'm not as concerned about accuracy as I am about finding a consistent way to measure my fitness.

[chicagogal]

Thanks for the explanation, TxDoc!

One problem I have with estimating my FTP other than the boredom factor for doing a 1 hr effort on the CT is that in general, my 20km TT is much better compared to my 40km TT. This is going by how I place relative to others, particularly in Merckx-style TTs. So, what does that mean for my FTP? That it really is pretty low but I probably follow more of a pursuiter power profile? (I haven't tested it, but I'd guess that to be the case). So, when doing FTP-based CT workouts (erg files programmed to put you at x % of FTP for each interval), should I continue to set my FTP on the high side considering that those workouts are relatively short?

One day, an SRM will be in the budget. One day.

For training on the CT, I don't think that accuracy of the FTP calculation is all that important. You just need a number that is within a reasonable margin of error such that your workouts aren't so easy that you are getting no training benefit or so difficult that you can't complete them. Also, if you have been using a certain FTP test, stick with that for now to gauge improvement, and raise the FTP number on your CT profile as you record improvement.

[Susan Otcenas]

I've been taking a coached, power-based cycling class (on Cycleops freewheel stationary bikes with Powertaps) for the last 3 months. After 1 month of base building, we tested our FTP, then did it again at the end of 3 months.

The raw data is interesting to me, but what mattered most was seeing an improvement over time. To me, that's the key. There may be a flaw in testing indoor vs. out, or 1 hr vs. a % of a shorter interval, but as long as you run the tests apples to apples, then you have a basis for judging improvement.

I test out at 3.4 w/kg. I'm hoping to both increase the numerator and decrease the denominator!

Susan

[TxDoc]

One problem I have with estimating my FTP other than the boredom factor for doing a 1 hr effort on the CT is that in general, my 20km TT is much better compared to my 40km TT. This is going by how I place relative to others, particularly in Merckx-style TTs. So, what does that mean for my FTP? That it really is pretty low but I probably follow more of a pursuiter power profile? (I haven't tested it, but I'd guess that to be the case).

Yes and No...
If your average power for 20' TT or 30' TT is much higher than your avg power or normalized power for 60' TT, the main thing this tells you is that your muscles fatigue much more after 30', which makes it hard for you to sustain a high power output when the effort lasts longer.

The 'profile' you refer to when you speak of 'pursuiters' (high sprint max, and big drop moving towards threshold) is the so-called power profile.
What the power profile tells you is where your power/weight is in each area. In fact usually it takes 5'', 1', 5', 20'. So the power profile by definition looks at sprinting power (5''), anaerobic (1'), VO2max (5'), and FTP (20'). What it does is paint a picture of what your cycling abilites are in the various zones. When you look at the power profile - yes, you may differentiate sprinters from time trialists, pursuiters, etc.

What you are actually doing, by comparing 20' and 60' - is to compare different tests in the same zone, which in this specific case is the lactate threshold area. So in fact, when you do that, you are looking at what most people call the fatigue profile and not at the power profile. The fatigue profile looks at one zone, and determines what is the status of your fatigue resistance.
For each zone there are some set percentages that coaches use to define fatigue resistance below, above, or at average. So you could make one fatigue profile for the VO2max zone, one for the threshold zone, etc...

In simple words - the power profile compares different zones, while the fatigue profile is specific to one zone.

So in your case, if you want to look at the lactate threshold zone - take your average power from your 20' TT, from 60' TT, and from 90'TT. If you do not have TT data for 60' and 90' you can use normalized power at 60 and 90 from a hard ride, although it will not be as accurate (but very very close!).
In average, we usually expect that the 60' value will fall between 4% and 6% lower than your 20' value. Likewise, the expected average for the 90' value is about 8-14% lower than your 20' value.
If you notice a larger drop when you compare 20' and 60' (i.e. your 60' value is less than 94% of your 20' value), what this tells you is that your fatigue resistance at threshold is below average.

Not sure this is written in a way that sounds reasonable, I'm post-call and kind of tired tonight so I may speak some nonsense...
If you would like some tables or info to calculate your profiles send me a PM, I can probably send you some.

And again if you want to test your fatigue profiles, CT is fine for threshold and maybe VO2max depending what you work on - but less accurate when you talk max, so the neuromuscular and anaerobic levels are harder to test well on CT.

So, when doing FTP-based CT workouts (erg files programmed to put you at x % of FTP for each interval), should I continue to set my FTP on the high side considering that those workouts are relatively short?

If most of the intervals in your workouts are within the 20 minutes duration or so, yes you could as well use the FTP value that you calculate either from a 30' TT or from a standard 95% of your 20'TT average power. For short interval workouts the % error would not be that much.

One day, an SRM will be in the budget. One day.

I guess this is where the CycleOps people did it right - the PT sits in between, with practically the same amount of data and accuracy of a quarq/SRM and a price which is not that much higher than a CT. And it allows cheap options - I'm one of those people who went cheap to begin with, and I still use a wired PT now that everyone has wireless computers... The benefits of collecting the data completely outweigh the hassle of seeing a wire on the bike and having to change wheels.

Good luck y'all, I'm going to sleep...