Conflicting instructions on Half Monty

I’ve just completed a Half Monty - first time and the beginning of a training plan - and totally don’t understand the results.

It’s not the meaning of the various metrics, it’s the instructions to ride the HR / recovery section at a HR of 151 to 156, which I did precisely, hitting 151 after about 2 minutes and keeping within 156 to the end. But then I got an error message in the results saying I rode at too high a power so the metrics are inaccurate. I hardly noticed the power as I was following HR and cadence, but it most seemed to be around 120w with a cadence of 90+/-3, after suggesting a starting power of 123w.

So is this section HR controlled or power? The instructions seem to emphasise the former. Any thoughts?

TBH I’m rather unlikely to keep on with a training plan if I can’t get a decent test every so often.

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After the ramp section (yellow staircase), you’re supposed to ride at a recovery pace (low power) to lower your HR and recover. I don’t remember the exact duration, but it’s about 7 minutes, and is shown by the low power blue section. You can ride this in ERG mode. In the picture, the 20 minute black section is the time at which you need to ride in slope/level lode at an appropriate cadence, and match the prescribed HR in the instructions.

If you rode the real recovery section at 151 bpm, that would explain the error message.

Here are detailed instructions:



Welcome @Drspeedy .

As @RServranckx has said, the HR target you were given (151-156 bpm in your case) is for the section with the orange box around it. It has no power target as you’re not aiming for a power level, just to keep your HR within the requested range.

The two minute lead-in to the 20 minute constrained HR effort is supposed to be at a recovery pace. I think the HR targets are usually Z1, but I often find I’m at low Z2, but that’s OK. Just pedal as easy as you can.

Can you share a screenshot of your activity history power profile with us? That way we might be able to better identify what happened.


Thanks for that RServranckx and way9e0, but I can clarify that it was the constrained effort, the section within the orange box, where there instructions were to ride with HR between 151 and 156, which I did. The recovery section before the ramp was ridden at the power spot on (in erg mode, so not difficulties). The the power in recovery after the ramp was a bit high (and I jumped off to start the fan as I was finally overheating - way too cold to start with the fan at 2C) largely because my cadence was too high, hence the faffing to get cadence, power and HR aligned in the next section.

On the power trace (below), the faffing about at the start of the constrained effort was trying to find a good gear in the ‘level’ mode that I hadn’t used before and get my heart rate up without overshooting. I hit 151 just before 40 mins, but to maintain that I had to ride at around 120 watts. When the power dropped below 110w, HR dropped to 149, so I usually upped the cadence to increase the effort. Then there was a general HR drift as expected over the 20mins so at the end I was maintaining 155bpm at about 117W.

But my question is why tell me to maintain a certain HR, and then when I do, tell me I was working at too high power when to reduce the power would mean dropping out of the target HR range? I don’t get it unless the aim is to force using a really high, inefficient cadence where you’ll get fatigue with low power. But I don’t think that’s the objective from my reading.


That zero power gap in the 2 minutes before the constrained effort I suspect caused the issue. From the instructions you need to maintain steady easy power there and I believe the calculation looks at the power/HR differences between this bit and the constrained effort. The error message is misleading, but this at least points to a place where the protocol wasn’t followed.

Leading into the Constrained: Like the portion leading into the ramp, ride this section steady. Smart trainer users should be in LEVEL mode at this point. Keep your power AT or BELOW the onscreen target for this section. Do not stop pedalling during this section. Do not surge during this section. Do NOT start the constrained effort early (meaning do not start the constrained effort during this lead-in section).


Thank you Tbronder
I was wondering about that, I guess I should have jumped off in the stop after the ramp.

It’s a steep learning curve since the old (definitely dumb, especially if they were rollers) trainers I used in the 90s, but I’m getting too old and rickety to ride outdoors in winter so needs must.

Thanks again for your collective help. I’ll doubtless be back with more dumb questions…


I agree with @tbronder that the dip in power at the start of the 2 minute recovery (Highlighted section 1) before the constrained effort is a potential issue.

The other possibility is that your power in the first part of the constrained effort is below the recovery effort. (Highlighted section 2).

I think the general expectation of this test is that you have a visible increase in power between the recovery portion and the 20 minute constrained effort. I don’t know what sort of data analysis the app is doing, but I can see how your power profile might not fit with what they are expecting.

Next time you try Half Monty, I suggest that you go straight to the ~120 W effort at the start of the 20 minute constrained section, and then adjust your power up or down slightly as your HR stabilizes. It sounds like you’ve also been through a learning process on gearing, cadence, and levels, so you can use that information for the next time you attempt the test.


@Drspeedy, here’s the power profile from a recent Half Monty test I did. I didn’t get any warnings or errors about the test results. Hopefully this gives you an idea of that profile you should be aiming for. I’ve highlighted the transition up in power from the recovery part into the 20 minute constrained test.

There should be a reasonably clean step up in power as you start the 20 minute constrained effort. I think based on your previous test, you now know that 120 W is a good starting point for that 20 minute constrained section.


Thank you very much for this great example of what I’m aiming for, Way9e0
I can but hope that in time my Half Monty power trace will be as smooth as yours, athough I doubt I’ll ever be looking at 300w again :grin:


Hi @Drspeedy
If you submit a support request at one of our customer support specialists (possibly one of the old Sufferfest Minions like me!) will be able to see your Half Monty details, results and a lot of metadata that you can’t see right from the graph.
We might find the answer is one of the ones you’ve been given here already, but it might be something else, so please reach out directly to us and we’ll get you the right answer as quickly as possible.


Many thanks Sir Alex
I will keep a note of this but I think the main thing is to have another go at the HM in the fairly near future and take my learning from this one, particularly the importance of the lead in to the constrained effort. In the meantime, I’ll practise on the Level setting too.

The stats might not be much better in a couple of weeks but the accuracy should be better (and I’m a scientist so I like to improve accuracy and precision where possible).