Half Monty Results - Not as accurate as Wahoo would like

Apologies if this should be on another thread such as 4DPvs Half Monty but did not want to risk opening up a 6 month old thread. And I cannot find in my search anything to do with the error.

Managed to squeeze in a Half Monty a day late on the plan @WahooCoach_Corey got this error message about accuracy.

My MAP and FTP both up 10 watts. What does this mean in effect? What would going too hard in the recovery section do to the results? Would it skew them to be higher or lower? i.e. if I’d not gone as hard in the recovery, would the actual FTP been higher or lower than given?

I have only done 4DP as mid plan tests in the past and thought I’d give the Half Monty a go, but feeling disappointed with it. It is not quite as hard as the 4DP, but didn’t expect an error. I thought I was within parameters and thought I’d not gone too hard in the recovery?

Also the constrained effort took quite a considerable amount of power for me to get my HR up. According to Strava and Laps when it uploaded, I had to average 251 watts to be in the suggested HR zone, which is only just below my previous FTP of 263. Although the 251 felt relatively easy.

I’m a little disappointed in not having improved more, but in reality with what life had thrown my way recently I am pleased to have improved at all, so I’m being pragmatic about it. The really frustrating bit is the error and not knowing if this is my actual FTP or not. I suppose I’ll see when I do this weeks training on the new power numbers.

I should have bitten the bullet and just done the 4DP, although I must admit to having been a little tired all the same, so perhaps not up to 4DP.

If anybody has any insights, that would be greatly appreciated.

FTP, MAP, and other metrics are defined as the results of a test. There is no underlying truth that’s being measured. FTP is originally defined as max 1 hr power. You do the 1 hr test, and you get a 1hr FTP. Other FTP test don’t measure 1 hr power. They do a different test, the results of which are then scaled to approximate what you might have done in an actual 1hr test. Comparing one type of FTP result to another type will only ever be approximate. Best to stick with one type of test, and do it exactly the same way each time, to quantify training results. For the most reproducible result, I do the 1 week test prep plan that includes a HM on day 3 and a FF on day 7. This gives a consistent lead in to the FF, and the HM sets suggested targets in the FF which greatly helps pacing it.


@FatSprinter - Hey man, you are doing great! @Saddlesaur is right when he says this is an approximation. And SYSTM is correct when it says you went too hard during the recovery, it should be easy. Now sweat man, I’d bump your FTP up to 270 and just go with that for this next block. You’ll be fine brother.

1 Like

Thank you both for the input @WahooCoach_Corey and @Saddlesaur - both taken on board. The plan called for a Half Monty, so that is what I did. It was supposed to update the figures for the remainder of the plan so I was training on fresh data. In the past I have done a 4DP instead of the Half Monty half way through a plan and regretted not doing it this time. I certainly couldn’t have fit in a one week test plan, nor would I think it suitable for a recovery week. I do entirely agree that I should have done the same test (4DP) that I’d done previously - just wish I’d felt a bit fresher to do it.

Whilst I understand that the tests under 1 hour are scaled using various protocols/methodologies and algorithms, (and indeed the recent information out there suggests that even the most trained athlete cannot sustain an hour using the FTP Figures from the standard FTP ramp tests) I expected the methodology of both the 4DP and the Ramp test to be based on vast amount of data that I am sure Wahoo has and would therefore be more reliable and would been closer in the data it spits out at the end of the tests.

I’ve upped the FTP so I’ll see what Sprints/Violator/Attacker feels like the next three days. It’s gonna be fun. Recover ride today, so lets hope legs are fresh for tomorrow. For info the 20 min Constrained Effort which averaged 251 Watts seemed doable and not too hard (not too easy either) so after the Ramp and holding 251 watts, I can imagine the FTP is around 270/273 easily.

Cheers again, it is going to be a Suffertastic next three days.

At least you can say half monty works for you. My last 4D results from December 2022:

My Half Monty from yesterday:

Based on how I’ve been feeling with my training so far half way thru my plan, those test results are bogus. I reset the numbers back to my full frontal numbers. If I’d really lost that much on my FTP, I’d be dying on every workout and as it stands right now I feel at times that some of the workouts aren’t hard enough which tells me I’m progressing.


Something clearly amiss there :confused:

Yes. The two tests will compare reliably for the very few riders who are at the average of the whole test cohort, but they won’t be for anybody else. For one half, they will be off one way, and for the other half, they’ll be off the other way.

1 Like

HM is an adapted ramp test.
Ramp tests are fine for everyone in the middle of the bell curve, but shockingly bad for outliers.

1 Like

I thought Wahoo had done is calculations to make it more applicable than standard ramp tests to take into account the variability of the riders and the standard bell curve distribution? I know that is what the 4DP is sold on, but not sure about the Half Monty, although in future I think I will just stick to doing the same test even half way through a plan when Half Monty is scheduled. Just for peace of mind and a more reliable set of metrics to base the future sessions on.

1 Like

yeah, i understand the feeling but gotta bear in mind–as other folks here have already mentioned–that all the calculations in the world don’t change that it’s an estimation of a thing, not a measurement of it.

I disagree that FTP has no underlying truth and is only defined by its test parameters. It definitely has an one (coaches and exercise physiologists have known about it at some level for decades), but that underlying truth is multifaceted and cannot be directly observed. The best explanation i have heard for the physiological underpinnings are that it is the maximum power that you can generate using almost solely aerobic sources, which explains Dr coggan’s “quasi-steady state” (i.e., above this threshold, you fatigue non-linearly faster) and also the lactate-based explanations (lactate accumulating means the contribution of anaerobic glycolisis is increasing). but the lactate test explanations are themselves observations of something indirect and, i believe, the tail wagging the dog.

So, back to the test protocols, they all have their advantages and disadvantages. 4DP is pretty dope because alongside an FTP estimate, it gives you a bunch of other information too for the same time investment. Ramp tests like Half Monty are also great because they don’t rely on pacing, so especially in early season where you’re not sure how hard you can go, you can get a great performance measure from a ramp test without the same learning curve. the one hour that Coggan and Hunter proposed as a gold standard (but again, according to coggan interviews, was thought of as a way of estimating, not a definitional parameter) is probably one of the best in terms of dialing a precise FTP (because you’ll get a feel for it), but it ignores the time component and that FTP will not be exactly 1 hour for everyone, plus it requires a decent chunk of focus. I think the classic 20 minute x .95 is the worst. just like using 220-age for max HR, it’s one of those things that as a population average probably fits well, but is gonna be way off for plenty of folks.

So where does that leave you?

I agree with @saddlesaur that using consistent tests is the best way to judge what progress you’re making.

practically, fully agree with @WahooCoach_Corey that the best way to figure out whether htose results = FTP is to do the workouts. if you’re fresh, FTP workouts shouldn’t feel all that hard until towards the end. Your legs should be complaining pretty hard but your breathing should be fine. use the workouts themselves to dial it in.


I’ll put it a different way. Two riders who do a good 1 hr max effort and get the same FTP will likely perform differently in a ramp test, and may perform very differently in other riding scenarios. Put those two equal FTP (and even equal W/Kg) riders in a race and it won’t end it a tie. In that sense, a hr max test only measures how well you can perform that specific test in a specific testing scenario.

The attractive thing about Wahoo’s 4DP system is that it adds different tests with the idea that those 4 test parameters more fully characterize a rider. But they are still just results from specific tests and testing scenario. Take two riders of identical weight and 4DP parameters, put them in a race, and it still won’t end in a tie, though it’ll probably be closer.


definitely agree with that!

1 Like