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Power Meter Brands
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Yeah, two legs would be bi-pedantic0
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While of course getting a full two legged power reading is the perfection, it can also be said that a true measure can only be taken when all the elements involved in the measurement have been recalibrated, something that is inhernetly a problem for all but lab testing (and pro teams I assume).
No it is available to home users. I did my PM over the summerWhat stages, PM2 etc are hopefully providing is a consistent reading. The number itself doesn't matter. Even if my L/R split is 70/30, and thus the PM reading is actually far too high (as it is taken the 70X2 rather than 100%) this will only be an issue in a stand alone test. It doesn't even matter if your pedalling style changes under different loads as again it just an indicative number.
it does matter if your pedalling style varies thats the problem.
55/45 at an "just spinning" could, and for alot of people does, turn into 70/30 under load.
In the case of changing balance its not even indicative, its just wrong.
Plus I want a power meter, not a power "lets make a number up"er
They say power is power everywhere in the world, but while that is true it is really w/kg that is the real reading.
Not really no. w/kg lets you swing your mickey around with respect to climbing, w/cda on the flat. However for training w/kg and w/cda doesn't matter its just watts and if they aren't consistent and accurate then why bother.Looking back at my cycles using the Stages and comparing the numbers to the calculators the numbers don't tally (unsurprising really) but I do see is a fairly consistent reading for power when looking at my training runs. Sutton, Killakee etc. The average W for the climbs are always the in around the same for the same sort of times (there are variances I assume due to wind, effeciency of the bike, tyre pressures etc).It would cause issues if I trained on a Stages and then raced with SRM as the numbers would not tally.
I would assume that many people getting stages and the like are using it as their sole PM, as such the actual number itself doesn't matter. As said before it could be 12 oranges or 20 pens.
But the numbers aren't consistent, gym work, new shoes, change in position many things could affect your l/r balance and now all your historical data is invalid for you.Based on training I know I can put out 200w for 10 minutes (per stages). In an event I will aim for 200w for ten minutes (again using Stages). Surely that is the point of a PM, to help train, and the gauge effort during events.
But in training you get a program that says 300w for 2 minutes as intervals lets say. But given how your balance may change at higher intensities you end up doing 270w or 330. The problem is you just don't know.0 -
SNIP
The prevailing wisdom is that most people have immaterial L/R power variances that do not adjust with power output. In my case this is true with my Powertap tracking perfectly with my Stages.
If your issues were common then it would be a problem, but in reality I don't think they are relevant.0 -
No it is available to home users. I did my PM over the summer
You calibrated it with what? How can you be certain that the readings are properly calibrated and that the computer is reading the data consistently. It is known that even the same PM can give out different PM's to different computersit does matter if your pedalling style varies thats the problem.
55/45 at an "just spinning" could, and for alot of people does, turn into 70/30 under load.
In the case of changing balance its not even indicative, its just wrong.
Plus I want a power meter, not a power "lets make a number up"er
I agree, but the split that stages uses is 50%/50%. It uses that no matter what. If your pedaling split changes under load, I think it is fairly safe to assume that it will consistently change under the same load. So the actual number at higher load is wrong in absolute terms, but once you are gauging it against itself then it will be consistenly wrong and thus not an issue.
I agree that it is an issue in terms of being able to gauge your numbers against others, but at the end of the day Pm reading wis not taken as the winner, time is.Not really no. w/kg lets you swing your mickey around with respect to climbing, w/cda on the flat. However for training w/kg and w/cda doesn't matter its just watts and if they aren't consistent and accurate then why bother.
But consistent to what? What exactly are are comparing against? Once the number is consistent against itself and over time then that is the usefulness or the PM.But the numbers aren't consistent, gym work, new shoes, change in position many things could affect your l/r balance and now all your historical data is invalid for you.
Yes, there are certianly things that can upset the numbers. A doubt any of time to mark a major change in a short period of time though. An the same can be said of any PM.But in training you get a program that says 300w for 2 minutes as intervals lets say. But given how your balance may change at higher intensities you end up doing 270w or 330. The problem is you just don't know.
Again, there is certainly room for some error, but I think we are talking about small margins here. You will know from your training what 270W for 2 minutes feel like. You're HR will be around the same, preathing etc. If you are suddenly at 90% HR when normally at 80% for the same Power that would clearly indicate a problem..
PM of all types are just a tool. They should not be used as the only point of reference. Thats fine for Froome etc who have the SRM bods only with them to constantly check the numbers but for the most part we don't have that sort of backing to allow us that level. What Stages, 4iiii, Brim etc are attempting to do is bring the PM to a wider audience, at a price point. Like every thing, you get what you pay for.
Is an SRM better than Stages, undoubtably so. Will I get better readings from the SRM, undoubtably so. Will the large extra expense be justified, in my case certainly not.
So I use my stages to try to take my training up a notch, be more focused. But I use my head more.0 -
I would assume that many people getting stages and the like are using it as their sole PM, as such the actual number itself doesn't matter. As said before it could be 12 oranges or 20 pens.
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the number does matter. the scale doesn't. you need the 12 to always be 12, it's whether it's a stages w or a different w that wouldn't matter if it was repeatable.
in that example, what if something external changes, one of the oranges isn't a orange, but a mandarin. now, is the scale still valid? the assumption that the relative measurement doesn't matter depends on one of two things
1) each step is the same (i.e. each actual 20w increase in power results in an increase in the measured power by the stages that may not be 20, but is the same amount each time. i.e., when you go from 110 to 130 in real watts the stages may report an increase of 15 (watts, oranges, apples, pens, whatever you want to call it). when you go from 220 to 240 you get an increase of the same amount, 15 (watts, oranges, apples, pens, whatever you want to call it). in that case that's fine
if your L/R balance stays the same over the entire power range, then that is true for the stages. if it changes though, then this won't be the case. it's not a relative measurement any more. now, a 20w increase at from 220 to 240 real watts means a change of 18, not 15 on your meter. same increase in real effort. different reading. if that's not important, then i'd question whether a pm is needed at all or not
2)the other way of doing it which rules out that issue is you know there is another variable in the equation, and you correct for it. so you know that at 220w your L/r balance is different to the balance at 150, and you compensate for it. you're basically eliminating the variable, and arriving back at a linear reationship, problem solved.
two of my rides recently:
AP: 171W NP:199W; LR bal:46/54
AP: 145W NP 152W; LR balance 49/51
First one a long bike with some pace efforts(3*40 mins) higher than the AP/NP numbers
second one an easy hour, whole ride done around the AP/NP level. if you do the maths on that balance at 200W real watts, left leg is 92w, r leg is 108. if i was trying for a target of 200w, i'd have driven the left leg to 100W to be doubled to 200, but I'd really be putting out 216W. Not far off 10% error. could be more as the power level gets closer to ftp and i'm pushing more
Based on training I know I can put out 200w for 10 minutes (per stages). In an event I will aim for 200w for ten minutes (again using Stages). Surely that is the point of a PM, to help train, and the gauge effort during events.
sure. how long can you hold 240w, based on that number? What L/R balance does that assume and are you confident that's the L/R balance you hold for that wattage??0 -
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Just reading all the post here on consistency of PM i have been using a power2max for the last 12 months and in the last 4 weeks i have been using a TT with a stages PM there i find a hug difference the stages definitely reads lower then my P2M but im not saying one is better than the other.
As with using any tool its about being consistent even if the numbers are high or low the numbers as long as you follow them they eventually become right .0 -
. Thats fine for Froome etc who have the SRM bods only with them to constantly check the numbers but for the most part we don't have that sort of backing to allow us that level. What Stages, 4iiii, Brim etc are attempting to do is bring the PM to a wider audience, at a price point. Like every thing, you get what you pay for.
Is an SRM better than Stages, undoubtably so. Will I get better readings from the SRM, undoubtably so. Will the large extra expense be justified, in my case certainly not.
So I use my stages to try to take my training up a notch, be more focused. But I use my head more.
you should have a look at this to see who froome uses...it's not srm, if it is it's well hidden..:
http://www.bikeradar.com/road/gear/article/pro-bike-chris-froomes-pinarello-dogma-f8-video-41608/
you're right on the stages working fine for some people as the errors don't matter for them, and it is more expensive to rule out those errors. for those that don't matter, stages or 4iii will do just fine.
for those who are trying to get the very most out of their training, the numbers are very important, even down to that level, and they'll end up paying for them.
i've no real issue with stages or 4iii. they fit a market niche. they're not for everyone. i do agree with the relative argument as well, in that it doesn't matter if they are off a bit as long as they are always off by the same amount, but people are ignoring a variable when applying it to stages/4iii which means this may not be the case and that bugs me a bit. probably unnecessarily so..:)0 -
Join Date:Posts: 21028
you should have a look at this to see who froome uses...it's not srm, if it is it's well hidden..:
http://www.bikeradar.com/road/gear/article/pro-bike-chris-froomes-pinarello-dogma-f8-video-41608/
I wish my bike had a moutain button0 -
The prevailing wisdom is that most people have immaterial L/R power variances that do not adjust with power output. In my case this is true with my Powertap tracking perfectly with my Stages.
If your issues were common then it would be a problem, but in reality I don't think they are relevant.
That may be the prevailing wisdom here, I prefer to listen to the likes of Alex Simmons http://alex-cycle.blogspot.com.au/2013/11/left-right-out-of-balance.html0 -
Join Date:Posts: 21028
That may be the prevailing wisdom here, I prefer to listen to the likes of Alex Simmons http://alex-cycle.blogspot.com.au/2013/11/left-right-out-of-balance.html
Is power balance data important/useful?
In short, we really don't know.
Good enough for me0 -
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You calibrated it with what? How can you be certain that the readings are properly calibrated and that the computer is reading the data consistently. It is known that even the same PM can give out different PM's to different computers
30kg of weights whose weight is known to 5gI agree, but the split that stages uses is 50%/50%. It uses that no matter what. If your pedaling split changes under load, I think it is fairly safe to assume that it will consistently change under the same load.
But that is not a safe assumption.So the actual number at higher load is wrong in absolute terms, but once you are gauging it against itself then it will be consistenly wrong and thus not an issue.
But its not, so it is still an issue. Albeit not for most users who just want to say they have power meters.I agree that it is an issue in terms of being able to gauge your numbers against others, but at the end of the day Pm reading wis not taken as the winner, time is.
Why would anyone compare wattages?But consistent to what? What exactly are are comparing against? Once the number is consistent against itself and over time then that is the usefulness or the PM.
All very true. However single leg measurement is not consistent with itself, for the same ride and even within the same ride.Yes, there are certianly things that can upset the numbers. A doubt any of time to mark a major change in a short period of time though. An the same can be said of any PM.
Eh no, because real ones measure the wattage, they don't guess at it based on one legAgain, there is certainly room for some error, but I think we are talking about small margins here. You will know from your training what 270W for 2 minutes feel like. You're HR will be around the same, preathing etc. If you are suddenly at 90% HR when normally at 80% for the same Power that would clearly indicate a problem..
If I want to yse heart rate why would I buy a power meter?PM of all types are just a tool. They should not be used as the only point of reference. Thats fine for Froome etc who have the SRM bods only with them to constantly check the numbers but for the most part we don't have that sort of backing to allow us that level.
Why not? the science is easy. Its because you don't understand it that you think single leg is validWhat Stages, 4iiii, Brim etc are attempting to do is bring the PM to a wider audience, at a price point. Like every thing, you get what you pay for.
Is an SRM better than Stages, undoubtably so. Will I get better readings from the SRM, undoubtably so. Will the large extra expense be justified, in my case certainly not.
Do you really need a power meter at all? Can you use it?0 -
Good enough for me
LOL you missed the point didn't you.
He was talking about the usefullness of the L/R metric as a training tool. Not on whether the measurement from the L versus LR was an issue. As in ensuring you ahd a 50/50 split rather than an asymmetrical varing one doesnt bring benefits"So, for instance, it's pretty common to see a different power balance at different power outputs as well as at the same power output but at different times during a ride."0 -
Again, there is certainly room for some error, but I think we are talking about small margins here. You will know from your training what 270W for 2 minutes feel like. You're HR will be around the same, preathing etc. If you are suddenly at 90% HR when normally at 80% for the same Power that would clearly indicate a problem..
You use HR to validate the accuracy of a power meter?????? Wow.
What do you use your power meter for?0 -
MOD VOICE: The general tone seems to have gotten aggressive in the last few pages. No idea why. We are a discussion forum. The next poster to be dismissive of another because they feel they know better can take a holiday. Discuss the issues, the power meters, the pros and cons, why you think they are pros and cons etc.0
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The contribution of legs to power generation is not consistent for anyone across a range of wattages. Nor is it consistent for someone at the same wattage over time within the same cycle. Nor is it consistent for someone across cycles.
Power meters operate in a world where a PM with an accurate of 1% has a huge advantage over one with 2% then introducing an unknown and variable inaccuracy is huge.
If the conversation needs to be elaborated on more than that for people to get the point and see the issue with single leg power meters, then I wish them the best .0 -
The contribution of legs to power generation is not consistent for anyone across a range of wattages. Nor is it consistent for someone at the same wattage over time within the same cycle. Nor is it consistent for someone across cycles.
Power meters operate in a world where a PM with an accurate of 1% has a huge advantage over one with 2% then introducing an unknown and variable inaccuracy is huge.
If the conversation needs to be elaborated on more than that for people to get the point and see the issue with single leg power meters, then I wish them the best .
If you have a a L/R imbalance that varies significantly at diff power outputs then the Stages or indeed any one leg solution will have issues.
In the case of reviewers, and in my own case, where the power has been compared with other meters that are crank or hub based no significant variation has been found that is outside of stated tolerances. No conclusive research has been done in the area so you mileage may vary.0 -
I really enjoy riding my bike.0
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If you have a a L/R imbalance that varies significantly at diff power outputs then the Stages or indeed any one leg solution will have issues.
In the case of reviewers, and in my own case, where the power has been compared with other meters that are crank or hub based no significant variation has been found that is outside of stated tolerances. No conclusive research has been done in the area so you mileage may vary.
What test protocol did you use? How did you record the data and then sub-sequentially compare it?0 -
bwalsh1983 wrote: »I really enjoy riding my bike.
What test protocol did you use? How did you record the data and then sub-sequentially compare it?0 -
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bwalsh1983 wrote: »I went out one day and my brain told me that I was enjoying it so I subsequently went out the next day and the sensations were equal.
But did you measure enjoyment from the left hemisphere of your brain or both?0 -
What if you cannot afford a dual leg pm will you get no advantage from training using a single leg pm the only affordable option for most?0
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What if you cannot afford a dual leg pm will you get no advantage from training using a single leg pm the only affordable option for most?
People often confuse cost with value.
If it was me I would save a few hundred more and get one (second hand or P2Max) whose data is more trustworthy.0 -
If it was me I would save a few hundred more and get one (second hand or P2Max) whose data is more trustworthy.
I haven't read through all the comparisons, or even the entire thread but is trustworthy the right word?
My understanding is that the data supplied by the single sided PM is relatively trustworthy, it is more that the way in which it is interpreted is not. If it was getting a dual sided PM would not provide any other advantage. Simply doubling the wattage may be reasonably close for some athletes, but it won't be in all conditions, on all days, in all circumstances.
Dual PMs give all the data (well not all, due to variations in how the data is collected) but if there are discrepancies there, they can be seen instantly. For those who have mentioned earlier that they are unconcerned with the accuracy of the numbers compared to other PMs, just the relative accuracy of the PM across its own range e.g. if the wattage doubles, the PM being used doubles it's numbers, in this case a dual PM is far more useful as it can remove alot of potential discrepancies in data collection.0 -
I haven't read through all the comparisons, or even the entire thread but is trustworthy the right word?
I picked this word carefully. I, personally, want to be able to know that if I am training to power that the numbers being displayed and recorded are accurate, that I trust them.
For those reasons if the calibration of a power meter can not be user verified, if not set, that thats an issue for me.
Garmins are out as head units for me (they have an issue in and around recording of zero values when you stop pedalling, not an issue in a hill climb or straight TT but on a road race, training spin or crit it is)
And I want data to be consistent.
For me my LR balance changes over the course of a year, the more trained I am the less it is. It also changes year on year. I have the guts ten years of power data available in WKO. Each power meter has been professional calibrated and personally verified. I can accurately and confidently do historical analysis of data.My understanding is that the data supplied by the single sided PM is relatively trustworthy, it is more that the way in which it is interpreted is not.
This statement I agree with. Yes it is a 98% accurate reading of the power generation of the left leg. I don't think anyone would disagree with that.If it was getting a dual sided PM would not provide any other advantage. Simply doubling the wattage may be reasonably close for some athletes, but it won't be in all conditions, on all days, in all circumstances.
Agreed. The 98% accuracy of the left leg does not mean 98% accuracy of the total power when doubled. Its a variable, and unknown inaccuracy.Dual PMs give all the data (well not all, due to variations in how the data is collected) but if there are discrepancies there, they can be seen instantly. For those who have mentioned earlier that they are unconcerned with the accuracy of the numbers compared to other PMs, just the relative accuracy of the PM across its own range e.g. if the wattage doubles, the PM being used doubles it's numbers, in this case a dual PM is far more useful as it can remove alot of potential discrepancies in data collection.
But the point is that a left only PM is only accurate across its own range for the left leg. Not the total power.
Not lets be honest most power meter users don't care about accuracy, don't care about repeatability, don't care about historical consistency. They just want to talk about their max wattage and NP for their ride with others.
Its getting like HR monitors were, everyone has one, no one knows how to use them. Thats fine.
Also:
Is this formula going to prevent micro breaks with the right leg?
P=2x((Fx9.9xl)x(Rx0.1047))
Not convinced.0 -
tunney wrote:If I want to yse heart rate why would I buy a power meter?
I think you are in danger of undermining, or perhaps just derailing, your own argument here by seeming to dismiss heart rate. Personally I agree that measuring one leg’s power output and doubling it is not ideal, I suspect that most people feel the same way, I think that where views start to differ is in whether measuring one leg’s output is “sufficient” - there is no easy answer to that, it drags in so many factors (convenience, training aims, commitment to training, cost, etc.) that the answer will vary from one person to another.
But even the best power meter should only be one of several training tools as far as I am concerned. Certainly for me, if I don’t monitor my heart rate too then I could delude myself that a session where I maintained 250W for 5mins was a marked improvement over a previous session where I could “only” sustain 240W for 5mins - it takes on a very different slant if I can see that my heart rate was at 95% of max for the 250W interval and at 30% of max for the 240W interval (I’m making up arbitrary numbers here).
Power info is very useful, but so too is heart rate info, and cadence, and sleep patterns, and dietary record, etc. But not everyone wants to, or is willing to, record and keep track of that level of detail. Which is fine. Nor does everyone need to either, some people progress without using any technological tools (which I find both impressive and nauseating, because I am shallow). Similarly, a power meter which is not absolutely accurate is enough for some people - sure, some of them may delude themselves that their power meter is entirely accurate and definitive, which doesn’t help their training, but others are happy to knowingly accept a greater margin of error than they’d achieve by throwing a lot more money at the problem and I see no issue with that.
From an entirely academic point of view, none of us should really settle for a power meter that falls outside a very narrow margin of error, but from an entirely practical point of view there are many valid reasons to do so. I personally find it very useful and interesting to read discussions about the pros and cons of various power meters, I want to make informed choices when I buy anything and training tools in particular and such conversations help to inform me, but such conversations can easily veer off in the direction of criticising rather than informing and then they start to lose all value as the facts get drowned out.0 -
^^I had a long diatribe about all the points raised by this thread on the use of PM's, the usefulness of L/R measurement etc.
I wrote it in a word doc last night and was just about to post, when Doozerie said it all more succinctly.
I therefore applaud him for his remarks, but ask the question as to why he waited until just now to post and not earlier thus saving me all the time and hassle?0 -
On another point, a lot of what I have read in magazines and online tends to suggest that the Powertap is a reliable and consistent power meter, and when people discuss potential inaccuracy they tend to focus on the likes of Stages which use extrapolation (or guesswork, depending on your point of view) to derive the power figure they display.
It's easy to conclude that there is a world of difference between Powertap and Stages, and while there are indeed clear distinctions in some respects, the boundaries can get very blurred over time. To take a specific example, if you replace the bearings in your Powertap yourself, then you won't have the means of confirming that it remains accurate afterwards. I replaced the bearings in my Powertap within a year, because the bearings were muck (or poorly installed at the factory, more likely), and while the power figures it has displayed since then seem to be in line with what it showed before, I've no idea whether it remains accurate, in reality. I could, of course, have had the bearings replaced by someone official like Paligap, but that's not cheap.
When you factor in the potential cost of maintaining a Powertap (I'm hoping it won't need new bearings every year, but who knows), and the potential loss of accuracy if you do the bearing replacement yourself, then Stages can start to look more appealing despite the possibility that it is not as accurate as Powertap from day one.0 -
I think you are in danger of undermining, or perhaps just derailing, your own argument here by seeming to dismiss heart rate.
If I wanted to train by heart rate why would I buy a power meter?
The specific person said that they use their heart rate to validate the accuracy of their power meter - paraphrasing here but "I know my power meter is right because my heart rate is consistently the same".
I was not dismissing heart rate as a metric.
When I was training properly I knew what a certain wattage should feel like and what heart rate I would typically be at. If for a given wattage my heart rate was elevated, or RPE off, then I knew that I had a problem. I was sick, overtrained or just having a bad day.
However if you cannot be sure of the power then those comparisons go out the window.Personally I agree that measuring one leg’s power output and doubling it is not ideal, I suspect that most people feel the same way, I think that where views start to differ is in whether measuring one leg’s output is “sufficient” - there is no easy answer to that, it drags in so many factors (convenience, training aims, commitment to training, cost, etc.) that the answer will vary from one person to another.
Sufficient for a particular persons needs. Yes granted a one leg device may be. So might an iBike, or a powercal. But lets not confused some that accurately measures power with something that is "sufficient".But even the best power meter should only be one of several training tools as far as I am concerned. Certainly for me, if I don’t monitor my heart rate too then I could delude myself that a session where I maintained 250W for 5mins was a marked improvement over a previous session where I could “only” sustain 240W for 5mins - it takes on a very different slant if I can see that my heart rate was at 95% of max for the 250W interval and at 30% of max for the 240W interval (I’m making up arbitrary numbers here).
Agree completely. HR, RPE and Power are needed in combination.
AgreePower info is very useful, but so too is heart rate info, and cadence, and sleep patterns, and dietary record, etc. But not everyone wants to, or is willing to, record and keep track of that level of detail. Which is fine. Nor does everyone need to either, some people progress without using any technological tools (which I find both impressive and nauseating, because I am shallow).Similarly, a power meter which is not absolutely accurate is enough for some people - sure, some of them may delude themselves that their power meter is entirely accurate and definitive, which doesn’t help their training, but others are happy to knowingly accept a greater margin of error than they’d achieve by throwing a lot more money at the problem and I see no issue with that.
Absolutely fine. Its the pretending some thats accurate when it isn't is what I am objecting to, not the fact its not accurate.From an entirely academic point of view, none of us should really settle for a power meter that falls outside a very narrow margin of error, but from an entirely practical point of view there are many valid reasons to do so. I personally find it very useful and interesting to read discussions about the pros and cons of various power meters, I want to make informed choices when I buy anything and training tools in particular and such conversations help to inform me, but such conversations can easily veer off in the direction of criticising rather than informing and then they start to lose all value as the facts get drowned out.
I really don't understand why someone would go one legged when for a small amount (relative) more you could get both legs.
but hey, some good points.0 -
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I therefore applaud him for his remarks, but ask the question as to why he waited until just now to post and not earlier thus saving me all the time and hassle?
All that time and hassle that you spent now will make you stronger and faster for the next debate, so I was just thinking of your best interests
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