Stages power meter

dw300

philhul wrote:

Did my first ride on the turbo/trainerroad yesterday with the stages. It's my first and only power meter so nothing to compare it against. Appreciate it's not going to be truly accurate but will be fine enough for what I need.

Seriously considered the power2max but already have SRAM Red and Force cranks and didn't want to have to buy another, plus rings. Whilst swapping a crank isn't the end of the world it's far easier to swap just the one arm between my bikes.

And how does the Virtual Power compare to the power meter?

FHKJ

Mccaria, I've run my new Stages alongside Power2Max and Powertap and it is seriously close. For training it is perfect, and matches my Wattbike to the Watt.

philhul

dw300 wrote:

And how does the Virtual Power compare to the power meter?

I can't compare unfortunately. I'd only done 3 rides on trainerroad without it and hadn't pushed hard enough on the test so my first ride was to retest. The turbo went on a higher resistance setting too.

dw300

philhul wrote:

dw300 wrote:

And how does the Virtual Power compare to the power meter?

I can't compare unfortunately. I'd only done 3 rides on trainerroad without it and hadn't pushed hard enough on the test so my first ride was to retest. The turbo went on a higher resistance setting too.

Yeh, but can't you do a test ride with your Garmin (or whatever computer you have on the bike) logging your power meter, and TrainerRoad logging virtual power from your speed/cadence sensor?

Just a 15 mins spin riding at a range of different powers etc, and trying to heat up your turbo to see if it drifts with temperature.

philhul

Good thinking. I'm in Mallorca until next Saturday but I'll try that when I get back.

Having the power meter out here is depressing. I knew I was rubbish but this just rubs my face in it! A winter of Trainerroad should hopefully sort me out for next year tho.

dw300

philhul wrote:

Good thinking. I'm in Mallorca until next Saturday but I'll try that when I get back.

Having the power meter out here is depressing. I knew I was rubbish but this just rubs my face in it! A winter of Trainerroad should hopefully sort me out for next year tho.

Cool. Let us know how it goes. Enjoy your holiday!

jon208

I've just done a 20 minute turbo session running both the Stages and a Powertap. The powertap was linked to my Garmin 705, Stages paired with my iPhone via Bluetooth.

Plenty of variables there - Garmin doing 3s averaging, I think the Stages app was instantaneous; ANT+ vs Blutooth etc etc.

I haven't got the ability or time to make pretty graphs like DC Rainmaker but my general observation is that (for me at least) the two units provide a very similar readout. The difference between the two was greatest when soft pedalling below 100W - possibly due to a greater % of loss through the drive train at lower power?

Most of the effort was done between 280 - 300W and both units were giving very similar values, i.e I think either could be used to stay in a chosen training zone.

At the end of the session I (briefly!) took it upto 600W. The two units were very close at the higher output.

Overall, so far I'm impressed. Really couldn't be easier to install. Pretty much fit an forget. Only weighs around 15g. Very happy with it so far.

Clearly it's not for everyone, especially those with issues with L/R balance (secondary to injury etc) and certainly not the tool for precise applications such as aero testing. But so far, for me, for the purpose of training within a given 20-30W zone I'm impressed.

Jon

slowbike

Thanks FHJK and Jon208 - you seem to be suggesting that for the less serious cyclist who only wants power as an indication/toy then the Stages PM is a consideration.
For me it seems a good way to get power without advertising the fact that you've got a power meter - no massive hub on the back wheel, no fancy spider in the crank ... it's a little disappointing that it's left side only, but understandable. It does make it easier to swap between bikes though and that could be quite handy (ok not as easy as a wheel based one).

jon208

Slowbike wrote:

Thanks FHJK and Jon208 - you seem to be suggesting that for the less serious cyclist who only wants power as an indication/toy then the Stages PM is a consideration.
For me it seems a good way to get power without advertising the fact that you've got a power meter - no massive hub on the back wheel, no fancy spider in the crank ... it's a little disappointing that it's left side only, but understandable. It does make it easier to swap between bikes though and that could be quite handy (ok not as easy as a wheel based one).

Hi
That wasn't really the point I was trying to make. From the experience I've had with the Stages unit so far I do not consider it a lesser unit for less serious cyclists after a toy. Admittedly the side by side comparison I ran with the Stages and Powertap was very informal and limited but the values returned by the two units were very similar. There's nothing to say either the Powertap or Stages was producing numbers which were more "correct" than the other. This may not be the case for everyone but for me it seems that the unit provides wattage values at least as useful for training within zones as the Powertap.

It probably isn't the tool to choose for equipment aero testing but realistically how many of know how to do that/actually spend time doing it. I know I don't.

I suspect that in certain circumstances the Stages may actually perform better than other PMs due to the constant temperature compensation it carries out. Not sure what effect going from 45deg on the valley floor to above the snow line on the Galibier has on a hit without this facility for example.

Very happy with my units I far.

Regards
Jon

teebs_123

Any further reviews of the stages PM? Looking to get one in the new year and would be interested in some first hand experiences.

The DC Rainmaker review of the latest software update looked promising.

99thmonkey

Ive got one, simple bit of kit and it just works, dont get hung up on the detail its a bloody good unit for the money and measures power exceptionally well. All I care about is what I can do and the steps of training to achieve that. I change it between bikes in less than 2 mins now so minimal and almost forget its there

teebs_123

Great, thanks. Just need to find somewhere with a 172.5mm Ultegra in stock.

lukasran

better take mine back then.

amaferanga

lukasran wrote:

better take mine back then.

The Stages is just a toy.

Mccaria

If it is a toy, then its a very good toy and I'm enjoying playing with it !

Very simple initial set up, works well with a Garmin 500, pretty much inconspicuous on the bike and ridiculously simple to move from one bike to another.

amaferanga

Stages have done a remarkable job of getting a lot of people to believe it's cheap (it isn't) and provides meaningful data (it can't).

Even proper power meters are simple to set up and swap between bikes so I'm really struggling to see what the appeal of Stages is. If it was a couple of hundred quid I'd understand, but it's as much or even more than a real power meter.

Mccaria

Hey Amaferanga,

I have a SRM 7900 and a SRM 9000 on road bikes and the data from the Stages on same route road rides is very similar - which confirms a static bike test I did indicating that I have a pretty even power distribution L-R. I think if you have a pretty even L-R output (or I good understanding of how they differ) then it is a useful tool.

I do like its portability and the ability to move from one bike to another in a matter of a couple of minutes. I use Shimano pedals, so the pedal based systems are currently out, have had a poor experience with Powertap and anyway prefer to use wheels of my choice. Of the Chainset based systems it is light, flexible and to date has given data consistent with that I would expect from my SRMs. Wouldn't swap it for the SRM, but as a point of entry into the power market, I think it is worth considering.

slowbike

madasahattersley wrote:

Might not be what some people want to hear but don't buy a power meter as a toy, buy one if you're a serious cyclist who wants to train themselves to get faster effectively. They don't make your cycling any more enjoyable (often less so) and are purely a training tool, not a toy and definitely not 'fun'.

You can say that about many ppls bikes ... all the "go faster" gear with little chance of ever being fit enough for it to make any noticeable difference ...

Power meter as a toy? Yes - that's all it would ever be - unless you're a Pro and you're making money from riding faster ... and anyway - more toys = more enjoyment - well, it can do if you don't take yourself too seriously ...

slowbike

amaferanga wrote:

Stages have done a remarkable job of getting a lot of people to believe it's cheap (it isn't) and provides meaningful data (it can't).

Even proper power meters are simple to set up and swap between bikes so I'm really struggling to see what the appeal of Stages is. If it was a couple of hundred quid I'd understand, but it's as much or even more than a real power meter.

Cheap? Nothing is cheap - power meters certainly aren't ... and nor is the Stages one, it's just the cheapest of the new kit atm.

So it measures the left leg power only - doesn't mean it's meaningless, it's just limited in the information that it can provide. For most leisure riders who are interested in power data without going overboard then it's one option.

As with all measuring tools, first you need to understand its limitations, then work out the application of the data that it's providing.

teebs_123

Mccaria wrote:

Hey Amaferanga,

I have a SRM 7900 and a SRM 9000 on road bikes and the data from the Stages on same route road rides is very similar - which confirms a static bike test I did indicating that I have a pretty even power distribution L-R. I think if you have a pretty even L-R output (or I good understanding of how they differ) then it is a useful tool.

I do like its portability and the ability to move from one bike to another in a matter of a couple of minutes. I use Shimano pedals, so the pedal based systems are currently out, have had a poor experience with Powertap and anyway prefer to use wheels of my choice. Of the Chainset based systems it is light, flexible and to date has given data consistent with that I would expect from my SRMs. Wouldn't swap it for the SRM, but as a point of entry into the power market, I think it is worth considering.

Thanks for that, it confirms what some of the independent reviews have stated.

amaferanga

Slowbike wrote:

amaferanga wrote:

Cheap? Nothing is cheap - power meters certainly aren't ... and nor is the Stages one, it's just the cheapest of the new kit atm.

So it measures the left leg power only - doesn't mean it's meaningless, it's just limited in the information that it can provide. For most leisure riders who are interested in power data without going overboard then it's one option.

As with all measuring tools, first you need to understand its limitations, then work out the application of the data that it's providing.

Um I think you completely missed the point. A lot of people are rushing out to buy a Stages, but if they can afford one then they can afford a proper power meter instead.

The limitation of Stages is that you'll never know if the number it shows is right. It could be out by a couple of Watts or it could be out by 50 or 100W. For a given person it could be spot on for one ride and several percent out on another. No one would accept that with an SRM or a PowerTap or a Power2max or a Quarq so why accept it with Stages.

With Stages you will never know how big the error is. That should be a deal breaker if you want a proper power meter.

So yeah, it's a toy.

slowbike

madasahattersley wrote:

Slowbike wrote:

madasahattersley wrote:

Might not be what some people want to hear but don't buy a power meter as a toy, buy one if you're a serious cyclist who wants to train themselves to get faster effectively. They don't make your cycling any more enjoyable (often less so) and are purely a training tool, not a toy and definitely not 'fun'.

You can say that about many ppls bikes ... all the "go faster" gear with little chance of ever being fit enough for it to make any noticeable difference ...

Power meter as a toy? Yes - that's all it would ever be - unless you're a Pro and you're making money from riding faster ... and anyway - more toys = more enjoyment - well, it can do if you don't take yourself too seriously ...

Yeah but spending more £££ on expensive bikes usually rewards you with an improvement in either speed, comfort or style.

Getting a power meter only makes you go faster if you bust your ass in training, it's not 'free speed' by any means, and I feel there are very few non-racers who ride purely to 'train hard and get fast,' for most there are other reasons to ride

Or just to have bragging rights .... Like many bikes in reality .... Style is just that!

slowbike

and here we have a review of the Stages Power Meter:
http://road.cc/content/review/98411-stages-power-meter

Interesting that they've compared it with the Powertap and Garmin Vector power meters too and found no significant difference overall...
and most crucially -

What is perhaps more important than the absolute figures is that the three systems tracked one another impressively consistently – not completely consistently, but always within those operating tolerances. Whether the power you put in is given a figure of 250 watts or 255 watts probably isn't that important to you, it's the fact that the figures you get are consistent that's more valuable and, for us at least, they were.

(my bold)

Alex_Simmons/RST

Slowbike wrote:

and here we have a review of the Stages Power Meter:
http://road.cc/content/review/98411-stages-power-meter

Interesting that they've compared it with the Powertap and Garmin Vector power meters too and found no significant difference overall...
and most crucially -

What is perhaps more important than the absolute figures is that the three systems tracked one another impressively consistently – not completely consistently, but always within those operating tolerances. Whether the power you put in is given a figure of 250 watts or 255 watts probably isn't that important to you, it's the fact that the figures you get are consistent that's more valuable and, for us at least, they were.

(my bold)

It is premature to make any conclusion when making a comparison with a Vector. Vector's themselves are prone to sizeable errors if not installed carefully.

Why don't they show the actual data, like say DC Rainmaker does, where you can readily see the sizeable variance and divergence in reported power from several devices (and ironically it's the left side that shows the largest variance in divergence) which just emphasises that 2 x left leg power is simply introducing an unknown and variable error.

The devil is in the detail, and there are far more clever ways to tease out these things than looking at average power. That is just lazy.

I've no doubt that the unit might well be within stated specification for the left crank arm, but it is highly misleading to project that same accuracy claim to total power, when it's a well established fact (IOW all the published research is consistent on this point) that asymmetry in power production is the norm, not the exception.

Again, that does not mean the Stages is useless, quite the opposite. One however just needs to understand its limitations and what data quality demands it is and isn't suitable for. For many uses, it will be adequate.

slowbike

Alex_Simmons/RST wrote:

I've no doubt that the unit might well be within stated specification for the left crank arm, but it is highly misleading to project that same accuracy claim to total power, when it's a well established fact (IOW all the published research is consistent on this point) that asymmetry in power production is the norm, not the exception.

I suppose it depends just how asymmetric your power output is - if it's within the tolerance of the PM then it will make no difference to overall output. If it's outside that then that raises some questions in itself I assume ...

Alex_Simmons/RST wrote:

Again, that does not mean the Stages is useless, quite the opposite. One however just needs to understand its limitations and what data quality demands it is and isn't suitable for. For many uses, it will be adequate.

Quite - although I'd say more than adequate - providing you know your general left/right balance split is minimal and you're not doing some sort of weird left/right leg training then I would think that the Stages more than fits the requirements.
One bit that was interesting from DCRM's second review was the need to re-calibrate the Quarq & Powertap as the temperature changes - a bit of a bugger on a long climb apparently ... something the Stages PM does not require.

IMHO for your average Jo the Stages is going to be sufficient in a technical sense.

amaferanga

How would your average Joe know that their left/right balance is 'normal'?

slowbike

amaferanga wrote:

How would your average Joe know that their left/right balance is 'normal'?

Go to somewhere with a wattbike or similar setup and find out?

But for the average Joe - it's not the absolute number that counts - it's the reliability and repetition of a number and the measured change over time.
Being able to average 300W over an hour is meaningless as it is - it doesn't translate directly into speed.

Team4Luke

Slowbike wrote:

amaferanga wrote:

How would your average Joe know that their left/right balance is 'normal'?

Go to somewhere with a wattbike or similar setup and find out?

But for the average Joe - it's not the absolute number that counts - it's the reliability and repetition of a number and the measured change over time.
Being able to average 300W over an hour is meaningless as it is - it doesn't translate directly into speed.

Amen to that

amaferanga

The number isn't repeatable if your L/R balance varies with e.g. fatigue, power, cadence. And it probably will.

Averaging x Watts over an hour certainly is not meaningless btw.

Alex_Simmons/RST

Slowbike wrote:

amaferanga wrote:

How would your average Joe know that their left/right balance is 'normal'?

Go to somewhere with a wattbike or similar setup and find out?

Then you'll need to think about what it's telling you, because left and right power balance is not as straightforward as it seems:
http://alex-cycle.blogspot.com.au/2013/ ... lance.html

Slowbike wrote:

But for the average Joe - it's not the absolute number that counts - it's the reliability and repetition of a number and the measured change over time.

Putting aside that accuracy and precision do tend to go hand in hand with instruments, the issue is there is an unknown and variable error. Because you don't know the size of that error, nor the conditions under which the error occurs or how it varies, then it means assessment of more subtle performance changes (or apparent changes) becomes problematic.

Slowbike wrote:

Being able to average 300W over an hour is meaningless as it is - it doesn't translate directly into speed.

It most certainly does if you know under what conditions that 300W is being applied.

Problem is, what happens when you start reporting 310W or 315W on your Stages but are not going any faster under the same conditions? Or conversly you are going just as fast under same conditions but on lower reported power? You will not be able to assess the reason for the change in that power-speed relationship because you cannot know if the reported power is real or an artefact of a change in pedalling dynamics (which is a normal thing to happen).

IOW one of the applications that has a higher demand on data quality is assessing how much speed you can get for your power. That's an application of the data for which a Stages is inadequate due to the unknown and variable size of the error in reported power.

So if that's not an application you care about, that's fine. Like I said, it helps for people to be aware of limitations and whether they are issues that would concern them.