Top end power loss

Alex_Simmons/RST

JGSI wrote:

I was going to dump Zwift last month... but I just find it too good a training tool to miss.
The races are filling up now with rocket fuelled Aussies , fighting fit as their season changes.

Aside from the few UCI pro races, our road season overlaps the Northern hemisphere as our road race season is held over our winter months. Summer is track and crit season here.

Alex_Simmons/RST

Slowbike wrote:

meanredspider wrote:

Alex_Simmons/RST wrote:

meanredspider wrote:

Alex_Simmons/RST wrote:

Slowbike wrote:

yup - thought it was - cos I seem to recall you discussing taking a onesided PM through the airport in hand luggage?

Anyway - mine is recorded with a Stages PM too - perhaps it's the age of the PM and nothing to do with the riders obviously AWESOME power - which far outstrips any pros ... or that's what we like to dream anyway

Stages are unreliable for measurement of peak power.

The figures I used to get were pretty consistent and I'd certainly trust it to tell me when I'm 30% down. If it were 5%, I wouldn't care.

I still wouldn't trust them for that purpose.

Without wanting to open up a whole "single-sided power" debate again, it's a strain gauge (array?) on a lever against which I apply force with my left leg. If all it's telling me is that my left leg peak power is down 30%, that's equally interesting to understand why

Exactly - it's not the absolute number that matters - it's consistancy in the result - something my Stages has been reliable at doing - I'm reasonably confident that my left leg is being trained (or not) at roughly the same rate as my right leg - last time I tried a wattbike the imbalance was minimal and quite frankly - the absolute overall power number doesn't matter (to me)

A power meter needs to be fit for the purposes to which you wish to put it.

When it comes to measurement of peak power capability discussed in this thread, the data the Stages provides is not consistent with the scientific literature on the well established relationship between peak pedal force and peak pedal velocity. It's not a problem confined to Stages BTW, just that Stages is particularly poor in this regard.

As for "all that matters is consistency", well as I often say it really depends on what you intend to do with your data. The Stages is not consistent across the entire power-duration spectrum relevant for human performance, so you need to be a bit more specific about what you mean. On average compared with a turbo trainer is hardly a high bar to meet and indicates it's suitable for a fairly limited range of uses of the data.

meanredspider

Alex - it would be useful to be pointed towards the Stages data. I'd be interested to understand why the device struggles to measure angular velocity. Does that suggest that the cadence data Stages generates is inaccurate? Again - I can believe that 1s power is inaccurate - one would have to question the value of that number anyway - but for more meaningful times, angular velocity would need to be very poor for it to affect the results significantly (for this discussion).

jgsi

Alex_Simmons/RST wrote:

JGSI wrote:

I was going to dump Zwift last month... but I just find it too good a training tool to miss.
The races are filling up now with rocket fuelled Aussies , fighting fit as their season changes.

Aside from the few UCI pro races, our road season overlaps the Northern hemisphere as our road race season is held over our winter months. Summer is track and crit season here.

whatever the season timings... a lot of Zwift downunder activity!

slowbike

Alex_Simmons/RST wrote:

Slowbike wrote:

meanredspider wrote:

Alex_Simmons/RST wrote:

meanredspider wrote:

Alex_Simmons/RST wrote:

Slowbike wrote:

yup - thought it was - cos I seem to recall you discussing taking a onesided PM through the airport in hand luggage?

Anyway - mine is recorded with a Stages PM too - perhaps it's the age of the PM and nothing to do with the riders obviously AWESOME power - which far outstrips any pros ... or that's what we like to dream anyway

Stages are unreliable for measurement of peak power.

The figures I used to get were pretty consistent and I'd certainly trust it to tell me when I'm 30% down. If it were 5%, I wouldn't care.

I still wouldn't trust them for that purpose.

Without wanting to open up a whole "single-sided power" debate again, it's a strain gauge (array?) on a lever against which I apply force with my left leg. If all it's telling me is that my left leg peak power is down 30%, that's equally interesting to understand why

Exactly - it's not the absolute number that matters - it's consistancy in the result - something my Stages has been reliable at doing - I'm reasonably confident that my left leg is being trained (or not) at roughly the same rate as my right leg - last time I tried a wattbike the imbalance was minimal and quite frankly - the absolute overall power number doesn't matter (to me)

A power meter needs to be fit for the purposes to which you wish to put it.

When it comes to measurement of peak power capability discussed in this thread, the data the Stages provides is not consistent with the scientific literature on the well established relationship between peak pedal force and peak pedal velocity. It's not a problem confined to Stages BTW, just that Stages is particularly poor in this regard.

As for "all that matters is consistency", well as I often say it really depends on what you intend to do with your data. The Stages is not consistent across the entire power-duration spectrum relevant for human performance, so you need to be a bit more specific about what you mean. On average compared with a turbo trainer is hardly a high bar to meet and indicates it's suitable for a fairly limited range of uses of the data.

Flippin eck you don't alf have an axe to grind over Stages Power Meter....

For us meer mortals, all that matters is consistancy - as you well know ...
There's no point me recording XX watts today and YY watts tomorrow if I've put out the same power on both days. Fortunately I don't believe Stages does that - its consistant - albeit unable to read the right leg power which has a major impact on the more instant readings.

At my age I'm not aiming for a Pro Cycling career and any racing I do is limited to TTs - so I'm after recording power during a sustained effort - both the turbo and the power meter have been reliable in provinding consistant data that I can compare myself against - if they're recording acurately then all the better - if there's a differential then so long as they always show that differential then it's all good. Who cares if I'm putting out XXX watts and the turbo/pm is showing XXY watts - I'm looking for a change in that XXY number - not the XXX - I don't even know what the XXX is.

Alex_Simmons/RST

meanredspider wrote:

Alex - it would be useful to be pointed towards the Stages data. I'd be interested to understand why the device struggles to measure angular velocity. Does that suggest that the cadence data Stages generates is inaccurate? Again - I can believe that 1s power is inaccurate - one would have to question the value of that number anyway - but for more meaningful times, angular velocity would need to be very poor for it to affect the results significantly (for this discussion).

It's the same reason Stages struggle on bumpy terrain and when pedalling is very stop/start in nature (ask many MTB riders with Stages about their data). The use of accelerometers and firmware to inspect torque peaks and troughs as a way to assess when the crank arm has completed a full revolution is prone to much error and random variation under such circumstances.

This discussion is about peak power. I would not trust a Stages to reliably report peak power of the left leg to within 10%, then layer on that the likely considerable variation in neuromuscular power balance, and I simply wouldn't rely on it for this purpose.

It's fine for other uses but this isn't one of them.

Alex_Simmons/RST

Slowbike wrote:

Flippin eck you don't alf have an axe to grind over Stages Power Meter....

For us meer mortals, all that matters is consistancy - as you well know ...
There's no point me recording XX watts today and YY watts tomorrow if I've put out the same power on both days. Fortunately I don't believe Stages does that - its consistant - albeit unable to read the right leg power which has a major impact on the more instant readings.

At my age I'm not aiming for a Pro Cycling career and any racing I do is limited to TTs - so I'm after recording power during a sustained effort - both the turbo and the power meter have been reliable in provinding consistant data that I can compare myself against - if they're recording acurately then all the better - if there's a differential then so long as they always show that differential then it's all good. Who cares if I'm putting out XXX watts and the turbo/pm is showing XXY watts - I'm looking for a change in that XXY number - not the XXX - I don't even know what the XXX is.

I have no axe to grind, merely pointing out a specific limitation with a particular use case of Stages power meter data.

If you wish to bury your head in the sand and think it doesn't exist, then carry on.

This thread is not about you and your TT power, it's about assessment of another rider's peak power. My point is that one cannot rely on Stages to consistently measure such peak neuromuscular power capability (Pmax) because of limitations in capturing such data due to the technology used by this meter (and as I have also pointed out the same problem exists for some other meters).

meanredspider

Alex_Simmons/RST wrote:

meanredspider wrote:

Alex - it would be useful to be pointed towards the Stages data. I'd be interested to understand why the device struggles to measure angular velocity. Does that suggest that the cadence data Stages generates is inaccurate? Again - I can believe that 1s power is inaccurate - one would have to question the value of that number anyway - but for more meaningful times, angular velocity would need to be very poor for it to affect the results significantly (for this discussion).

It's the same reason Stages struggle on bumpy terrain and when pedalling is very stop/start in nature (ask many MTB riders with Stages about their data). The use of accelerometers and firmware to inspect torque peaks and troughs as a way to assess when the crank arm has completed a full revolution is prone to much error and random variation under such circumstances.

This discussion is about peak power. I would not trust a Stages to reliably report peak power of the left leg to within 10%, then layer on that the likely considerable variation in neuromuscular power balance, and I simply wouldn't rely on it for this purpose.

It's fine for other uses but this isn't one of them.

I'm genuinely interested, Alex, as a nerdy engineer, to find out more detail. Is there a review for or study on this? Part of the reason I'm questioning this is that the figures were pretty consistent when I was riding consistently myself - I doubt that there was as much as 10% difference between rides for this peak power area.

Alex_Simmons/RST

meanredspider wrote:

Alex_Simmons/RST wrote:

meanredspider wrote:

Alex - it would be useful to be pointed towards the Stages data. I'd be interested to understand why the device struggles to measure angular velocity. Does that suggest that the cadence data Stages generates is inaccurate? Again - I can believe that 1s power is inaccurate - one would have to question the value of that number anyway - but for more meaningful times, angular velocity would need to be very poor for it to affect the results significantly (for this discussion).

It's the same reason Stages struggle on bumpy terrain and when pedalling is very stop/start in nature (ask many MTB riders with Stages about their data). The use of accelerometers and firmware to inspect torque peaks and troughs as a way to assess when the crank arm has completed a full revolution is prone to much error and random variation under such circumstances.

This discussion is about peak power. I would not trust a Stages to reliably report peak power of the left leg to within 10%, then layer on that the likely considerable variation in neuromuscular power balance, and I simply wouldn't rely on it for this purpose.

It's fine for other uses but this isn't one of them.

I'm genuinely interested, Alex, as a nerdy engineer, to find out more detail. Is there a review for or study on this? Part of the reason I'm questioning this is that the figures were pretty consistent when I was riding consistently myself - I doubt that there was as much as 10% difference between rides for this peak power area.

No study, only a few power meters have actually been subject to scientific study to assess their reliability. consistency and accuracy. Actually I think really only one model has had all of those done, a couple of others have had aspects assessed.

Post some peak power data from standing start maximal effort accelerations or maximal efforts from a very slow rolling pace. Up to 10 seconds of data for each effort. Power, cadence, crank length and/or plot the AEPF v APV* for the maximal efforts. It's a really basic test all power meter reviews should do, but don't.

*
Average Effective Pedal Force
Average Pedal Velocity

meanredspider

I'll see what I can do over the weekend. I'm pretty limited as to the computer capability i've got where I'm based right now but it should be possible. If I can I'll do both Neo and Stages - I can't escape the house as I'm babysitting my sick daughter.