The Froome Files, test data only thread

[Koronin]

In my experience as the sweat builds and your chest is expanding and contracting more under heavy breathing of big efforts, the HR readings can go a bit high sometimes outdoors. I don't race with a Head Unit, but I do at a 1.5hr Tuesday night Training Crit every week in the summer and several times you'll look downand think you're ill as the reading is just way too high. It can last a few seconds or a few minutes. My max HR is 174 and i've regularly seen it peaking around 190bpm and sometimes even 190bmp when i'm not even close to maximum perceived effort or high watts for a sustained period. You really just learn to take HR & Power with a pinch of salt when analysing the data in Training Peaks or whatever and smooth it out to get a more realistic idea. End of the day it's precise enough technology to track your progress if it's repeatable and that's all that matters long-term for training. The whole claim of things being +-2% accurate for HR monitors and Power Meters is based on a snapshot against a known power and HR, not how accurate it is with itself over the duration of a ride.

Here's a comparison between a HR Strap & HR watch on the road in the real world.


Here's the same two HR Monitors indoors on a Turbo Trainer.

Considering the fact that those plots come from an article showing that watch based optical systems are not as accurate as electrical-based chest systems in the real world, using them as examples of different HR monitors showing variation in readings without stating this is highly misleading.

There's no smoothing Gillan, that is the raw data. There's way more interference outside and of course you tend to move your body much less on a turbo and of course no rough ground and road buzz etc probably makes a difference with the HR watch as nearer the shaking of the bars on the road. I would never look at my HR or Power and take it 100% accurate. As long as it's repeatable each day, that's fine.

what I meant was that because of the nature of road riding then your heart rate will always be going up and down due to easing off in tailwinds, pushing a bit in climbs...slowing for cars, junctions, deer, other cyclists, crap road surface, puddles etc etc etc...i.e.the raw data is always going up and down

on a turbo its pretty consistent......

See my reply above. You are correct, a turbo will give a more consistent change (course dependent obviously) and SH is also right that the reduced movement on the turbo will stop the watch shaking.

The issue here is that when people talk about discrepancy between readings they would generally refer to comparable measurements made with two comparable devices in a similar situation, such as the turbo session. This is not the case here.The plots SH shows are from an article specifically pointing out that those devices are not comparable on the road. It's here:

http://www.bikeradar.com/gear/article/how-accurate-is-wrist-based-heart-rate-vs-hr-strap-48458/#disqus_thread

As you can see from the data SH posted, under controlled conditions, turbo, they are extremely similar, within a couple of beats of each other. Replace the watch in the on road test with another chest strap and it's likely to look very similar to the chest strap in this data.

Cheers KB (and SH) but is that not obvious? I'm assuming we're talking about measuring the HR at the wrist with the actual wrist unit? Of course it'll be different and the wrist one will perform unfavorably, or at least that would be my intuitive thought...I am talking about the comparison between two different HRMs both using chest straps, if they were sooooo different you wouldn't use it...so agree about that data being used being misleading

and, to be fair, I had misread the graphs in terms of the comparison so thanks for clarification on that point (both KB and SH)

I think everyone is talking about this, which is why it's so misleading for someone to use data from chest Vs. Watch devices on the road as an example of device variation.

Also don't almost all the riders in the peloton at least while racing only use the chest device? Valverde using a watch as well, but truthfully can't remember any other rider in the peloton wearing one during races.

[gillan1969]

Apologies for not going through all the pages but did Swart check for a motor on Froomes bike before the test?

Power was measured at the crank arms and at the ergometer load device. A motor would result in different power readings. They were not different.

cheers...so not explicit but implicit

that works

[thehog]

Apologies for not going through all the pages but did Swart check for a motor on Froomes bike before the test?

Power was measured at the crank arms and at the ergometer load device. A motor would result in different power readings. They were not different.

For argument sake let’s say he did have a motor during the test.

Crank has Stages so would measure the “strain” applied by the motor, the wind trainer is providing the resistance and is measuring power produced from where? The force of the roller, with resistance? He wasn’t using a standard ergo/jig. Which means a motor could be used depending on the type of motor & where it was placed.

[brownbobby]

Apologies for not going through all the pages but did Swart check for a motor on Froomes bike before the test?

Power was measured at the crank arms and at the ergometer load device. A motor would result in different power readings. They were not different.

For argument sake let’s say he did have a motor during the test.

Crank has Stages so would measure the “strain” applied by the motor, the wind trainer is providing the resistance and is measuring power produced from where? The force of the roller, with resistance? He wasn’t using a standard ergo/jig. Which means a motor could be used depending on the type of motor & where it was placed.

I don't see how any kind of motor could apply power to the upper middle part of the crank arm, which is where the strain gauge is on a stages PM.

[hazaran]

I don't see how any kind of motor could apply power to the upper middle part of the crank arm, which is where the strain gauge is on a stages PM.

That's before you consider strain gauges are not magic devices that measure cycling power as long as something touches them

It's one big statistical process and will only yield any sort of reasonable number when used in the manner it was trained, pushing down on the pedals.

[thehog]

I don't see how any kind of motor could apply power to the upper middle part of the crank arm, which is where the strain gauge is on a stages PM.

That's before you consider strain gauges are not magic devices that measure cycling power as long as something touches them

It's one big statistical process and will only yield any sort of reasonable number when used in the manner it was trained, pushing down on the pedals.

Stages doesn’t measure from the downward force on the pedal. It measures via the deflection in the crank arm when force is applied along with using an algorithm for temperature and torque - it doesn’t know where that force might come from.

[Alex Simmons/RST]

Apologies for not going through all the pages but did Swart check for a motor on Froomes bike before the test?

Power was measured at the crank arms and at the ergometer load device. A motor would result in different power readings. They were not different.

For argument sake let’s say he did have a motor during the test.

Crank has Stages so would measure the “strain” applied by the motor, the wind trainer is providing the resistance and is measuring power produced from where? The force of the roller, with resistance? He wasn’t using a standard ergo/jig. Which means a motor could be used depending on the type of motor & where it was placed.

Let me make this simple for you.

If there was a motor then it could power the rear wheel without any force being applied to the cranks.

Power at the rear wheel is measured via an electromagnetic brake control device - it measures the torque and rotational velocity applied to the trainer's roller.

IOW if there was a motor, then:
Power at the rear wheel/trainer's roller = Power of a motor + Power applied via the bicycle cranks

Since the power measured at the rear wheel was the same as the power measured at the cranks, the contribution by any motor (assuming this hypothetical device even existed) was therefore zero.

[Alex Simmons/RST]

I don't see how any kind of motor could apply power to the upper middle part of the crank arm, which is where the strain gauge is on a stages PM.

It can't. Bottom bracket motors apply their power downstream of crank arms.

[Alex Simmons/RST]

Stages doesn’t measure from the downward force on the pedal. It measures via the deflection in the crank arm when force is applied along with using an algorithm for temperature and torque - it doesn’t know where that force might come from.

No, it doesn't know (can be your feet/legs, or your hands, or something leaning on it) except that any such force must be applied to the crank arm itself. BB motors do not apply forces to crank arms.

[thehog]

Apologies for not going through all the pages but did Swart check for a motor on Froomes bike before the test?

Power was measured at the crank arms and at the ergometer load device. A motor would result in different power readings. They were not different.

For argument sake let’s say he did have a motor during the test.

Crank has Stages so would measure the “strain” applied by the motor, the wind trainer is providing the resistance and is measuring power produced from where? The force of the roller, with resistance? He wasn’t using a standard ergo/jig. Which means a motor could be used depending on the type of motor & where it was placed.

Let me make this simple for you.

If there was a motor then it could power the rear wheel without any force being applied to the cranks.

Power at the rear wheel is measured via an electromagnetic brake control device - it measures the torque and rotational velocity applied to the trainer's roller.

IOW if there was a motor, then:
Power at the rear wheel/trainer's roller = Power of a motor + Power applied via the bicycle cranks

Since the power measured at the rear wheel was the same as the power measured at the cranks, the contribution by any motor (assuming this hypothetical device even existed) was therefore zero.

I don’t think he had a motor, that we all agree, however the rear resistance was controlled at a set level, it wasn’t measuring his power output per se. You really only had one independent measurement of power which came from the crank arm.

The sub-maximal testing undertaken by Chris Froome required him to ride on his own bike connected to an ergometer that controlled the power independent of cadence. The test started at 250 watts and increased at a rate of 25W every four minutes. This test was done twice — once under ambient conditions, and once under hot and humid environmental conditions.

[Alex Simmons/RST]

I don’t think he had a motor, that we all agree, however the rear resistance was controlled at a set level, it wasn’t measuring his power output per se. You really only had one independent measurement of power which came from the crank arm.

The sub-maximal testing undertaken by Chris Froome required him to ride on his own bike connected to an ergometer that controlled the power independent of cadence. The test started at 250 watts and increased at a rate of 25W every four minutes. This test was done twice — once under ambient conditions, and once under hot and humid environmental conditions.

If only you would do even the least amount of cursory research before posting nonsense...

The test was performed on a Computrainer. It both measures the actual load as well as provides a means to control that load while cycling, if required. It is quite effective at doing both at the same time. This is ergometer 101.

It's not new technology, having been in use for decades with hundreds of thousands of such data files created every month on such ergometers. I own one myself and have performed hundreds of tests on them.