Stages L power meter, worth having?

[burglarboycie]

So like many others I have been waiting for the release of the Favero Assioma Duo Shi pedals but now the details have been released I (like many others) have been put off by the Q Factor issue and also the lack of Dura Ace pedal body compatibility. This has made me look at my other options. I want to stick with SPD SL so am ruling out the Assioma Duo and I don't have the budget for the Garmin Rally.
This has led me to the Stages left sided power meter. I should mention at this point that it's for my Caad12 with Hollowgram cranks. I like the idea of simply ordering a new left side crank arm and being good to go.
Is this my best option in people's opinion and what are you guys real world experience like with the Stages?
I understand that a single sided power meter does have its limitations and is somewhat of a compromise so would be keen to get some input from any users on here.

[pdlpsher1]

I have used both Quarq DFour and Stages L only PMs. For me the Stages is reliable (i.e. no dropouts) and accurate, just like the Quarq. For me personally I prefer the Stages over the Quarq mainly because I dislike the 30mm aluminum axle on the Quarq. With the Stages I'm able to run a Shimano crank with the 24mm steel axle. Whether you're a seasoned PM user or a first-time PM user you'll be happy with the Stages. And personally I don't think having a dual-sided PM is worth the extra expense/complexity. A single sided PM is good enough. Comparing the data from both PMs, the Stages tend to be a bit more 'jumpy' as compared to the Quarq where its data is smoother. This is due to the Stages being single sided and the power value is doubled. This is the only difference I could tell between the two.

[Dylanlspangler]

I have a Left arm power meter and love it. I was going to go with a stages but found this 4iii much cheaper. Lots of guys in my local club have stages and love them. Seem to be just as accurate and very reliable. I’m sure left arm power meters aren’t the most accurate device ever but I’ve found it to be useful data. Well worth the money.


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[Cycomanic]

We had discussions about this several times here. I'm firmly in the camp that single-sided PMs have only very limited usefulness, I let other weigh in on the a pro argument.

The problem with one sided power measurements is that your left/right balance varies with effort and cadence (and might not even be consistent over longer time). Because the one-sided PM calculates total power by doubling the single sided power. However, because of the variations of balance you get widely varying total power, which makes it extremely difficult (a.k.a impossible) to extrapolate on your abilities and use that for tracking and prescribing training.

Now if you are someone who has years of dual sided training dataand good knowledge/data about your l/r balance over all power ranges, you can probably get away with switching to a single sided PM and adjust those values. Similarly, if your just interested in getting some numbers while training without doing much with it, a single sided PM is likely enough.

However if you want to actually train with power you are much better off with a dual sided PM.

I also find the comment about Q-factor somewhat surprising. I think people are much to obsessed with it, and there is no research showing that there is a significant effect of small changes in Q-factor. In fact the difference between the q factor of MTBs and road bikes is significantly larger than variations between pedals etc. And people usually don't get of a MTB and say they can't ride on it.

I do understand your point about dura ace body version, but much of the greatness of those pedals is in the axle and bearings anyway, which you would get with the assioma. So my recommendation is to just go with the assioma SPD-sl and not worry about the change in q factor (which you can likely compensate/mitigate with cleatplacement). The difference of having a dual sided PM over single sided is much bigger than a small change in q factor.

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[HenryH]

Interesting. Any links to datasets showing that the difference between the two legs are that big?

I have only had one sided (Stages) and I have always thought there wouldn´t be much need for dual.

For the OP - anecdotally mine has been excellent. Only small issue has sometimes been that the battery goes flat after cycling in the rain. During the ride no issues, but occasionally the day after the battery will be dead. Happened 3-4 times over some years. I can´t remember which generation I got, but it isn´t the first because I believe they redesigned the battery cap for the version I got. Not sure if they have done further upgrades since.

[c60rider]

Team Sky when they were using single sided Stages found very little difference in power figures when using single to double. But the point you're missing is that if you only have one power meter on one bike then it's totally irrelevant whether it's single or double sided. As long as it consistently measures that power then it's relevant for the user to use. You can then compare power meter numbers from one ride to the next and from month to month. Consistent, reliable measurement is the most important factor.

[Cycomanic]

Interesting. Any links to datasets showing that the difference between the two legs are that big?

I have only had one sided (Stages) and I have always thought there wouldn´t be much need for dual.

For the OP - anecdotally mine has been excellent. Only small issue has sometimes been that the battery goes flat after cycling in the rain. During the ride no issues, but occasionally the day after the battery will be dead. Happened 3-4 times over some years. I can´t remember which generation I got, but it isn´t the first because I believe they redesigned the battery cap for the version I got. Not sure if they have done further upgrades since.

Not something available right now (on my phone), but remember say you pedal at 50/50 balance at threshold and your balance changes to 45/55 when you do a 4 min interval at 400W say, the difference in power is 40W. If you prescribe your intervals as percentage of FTP this will determine if you can make the interval or it lasts 2-3 min. 2-3% fluctuations are fairly common just riding along, but 5% l/r fluctuation when really pushing hard is nothing special either.

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[Cycomanic]

Team Sky when they were using single sided Stages found very little difference in power figures when using single to double. But the point you're missing is that if you only have one power meter on one bike then it's totally irrelevant whether it's single or double sided. As long as it consistently measures that power then it's relevant for the user to use. You can then compare power meter numbers from one ride to the next and from month to month. Consistent, reliable measurement is the most important factor.

Many people have questioned sky's honesty about this, they likely used SRM or other dual sided options for testing. However, it's important to remember that pros fall under the type of people who already have tons of data at every effort level. Moreover pros are incredibly good at riding to a certain exertion level even without a PM. So what applies to pros does not always apply to amateurs.

Regarding your point on just tracking and comparing numbers month to month. Sure if your just interested in looking at the numbers, but if you regularly test e.g. your FTP and the do intervals based on the changed ftp you will set wrong limits. Moreover, if you're working on some weakness (e.g. 2min power), you will not know if your changes are based on variation of l/r power or actual fitness. Sure you could always test over a broad range of CPs, but who wants to do that. The disadvantages are really not worth the savings.

There have been quite a few discussions on the wattage group (now largely dormant) about this.

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[nickf]

I have stages L arm on 2 of my bikes. Road and gravel. No dropouts and no issues. Also very consistent, zero reset before each ride. Great app for firmware update. Battery life is decent at best, I keep 2032s on hand. My coach can't tell a difference between my 2 bikes and the numbers. Both read very closely to one another. Excellent training tool.

[ViperFFM]

Have a 4iii since 2 years and power is 99% accurate compared to a kickr v5.

Chances that your are imbalanced by 45/55% l/r are very very slim. Go for a bike fit to check and as long as it's in the range of 48-52% go for the one-sided.

[tritiltheend]

Interesting. Any links to datasets showing that the difference between the two legs are that big?

I have only had one sided (Stages) and I have always thought there wouldn´t be much need for dual.

For the OP - anecdotally mine has been excellent. Only small issue has sometimes been that the battery goes flat after cycling in the rain. During the ride no issues, but occasionally the day after the battery will be dead. Happened 3-4 times over some years. I can´t remember which generation I got, but it isn´t the first because I believe they redesigned the battery cap for the version I got. Not sure if they have done further upgrades since.

I'm not aware of any datasets on occurence of leg imbalance, maybe a pubmed search would produce something. But it's not that uncommon, there are a number of threads on this topic on Slowtwitch and quite a few folks have chimed in with imbalance issues. Both my wife and I got junk numbers out of a single-sided Stages that came with a second hand bike she bought. All our other power measureing devices match (Quarq, Assioma Duo, Power2Max & Saris H3). In my case the Stages read 10% high on average power as I'm L leg dominant, but the discrepancy was higher at low power and less at high power.

I would not purchase a single sided meter unless you had a chance to verify with a loaned power meter with independent L/R readings that you do not have an imbalance.

[Mcdeez]

4iiii> stages

[Lemond75]

I've got 2 Stages PM's - one Shimano and one Campagnolo. THe early generation models had issues with leaky seals, but they were replaced by Stages (who I have to say provide great customer service here in the UK). Since having the Gen2 models, both PMs have been flawless.

[HenryH]

Interesting. Any links to datasets showing that the difference between the two legs are that big?

I have only had one sided (Stages) and I have always thought there wouldn´t be much need for dual.

For the OP - anecdotally mine has been excellent. Only small issue has sometimes been that the battery goes flat after cycling in the rain. During the ride no issues, but occasionally the day after the battery will be dead. Happened 3-4 times over some years. I can´t remember which generation I got, but it isn´t the first because I believe they redesigned the battery cap for the version I got. Not sure if they have done further upgrades since.

Not something available right now (on my phone), but remember say you pedal at 50/50 balance at threshold and your balance changes to 45/55 when you do a 4 min interval at 400W say, the difference in power is 40W. If you prescribe your intervals as percentage of FTP this will determine if you can make the interval or it lasts 2-3 min. 2-3% fluctuations are fairly common just riding along, but 5% l/r fluctuation when really pushing hard is nothing special either.

Sent from my LYA-L29 using Tapatalk

Interesting. Any links to datasets showing that the difference between the two legs are that big?

I have only had one sided (Stages) and I have always thought there wouldn´t be much need for dual.

For the OP - anecdotally mine has been excellent. Only small issue has sometimes been that the battery goes flat after cycling in the rain. During the ride no issues, but occasionally the day after the battery will be dead. Happened 3-4 times over some years. I can´t remember which generation I got, but it isn´t the first because I believe they redesigned the battery cap for the version I got. Not sure if they have done further upgrades since.

I'm not aware of any datasets on occurence of leg imbalance, maybe a pubmed search would produce something. But it's not that uncommon, there are a number of threads on this topic on Slowtwitch and quite a few folks have chimed in with imbalance issues. Both my wife and I got junk numbers out of a single-sided Stages that came with a second hand bike she bought. All our other power measureing devices match (Quarq, Assioma Duo, Power2Max & Saris H3). In my case the Stages read 10% high on average power as I'm L leg dominant, but the discrepancy was higher at low power and less at high power.

I would not purchase a single sided meter unless you had a chance to verify with a loaned power meter with independent L/R readings that you do not have an imbalance.

I can certainly see the logic behind it. I'm just wondering how big of an issue it would be in real life and for how many.

I have really no clue as to how dominant one leg is vs. the other on average. Is it 1%? Is 5% normal or is that extreme? Or would 99% have less than 1% difference?

The same in the different zones. If you are 3% off at FTP is it then even possible to be 10% off at FTPx2 or is that normal? Does it change much as you are getting more tired?

If everything is reasonably stable across does it then matter in the end if the values are off? If I got one dominant leg meaning values are 3% off which then becomes 6% off, but it is more or less the same at FTP or FTPx3 then I guess I would just naturally adjust my training accordingly?

I haven't thought much about the issue before I saw this thread. The only comparable values I got for myself are on my Kickr and they are reading so closely I couldn't really tell which one is which one across datasets. That doesn't mean that my Stages reading are correct of course and I couldn't say if that is uncommon.

[burglarboycie]

Thanks for all the responses guys.

But the point you're missing is that if you only have one power meter on one bike then it's totally irrelevant whether it's single or double sided. As long as it consistently measures that power then it's relevant for the user to use. You can then compare power meter numbers from one ride to the next and from month to month. Consistent, reliable measurement is the most important factor.

I think c60rider makes a valid point here, it will be my first and only experience riding with power so as long as it tracks consistently I have nothing to compare it against but will still see improvement with these figures no matter how accurate/inaccurate they are. However, part of me doesn't want to 'settle' for what almost seems like a make do method. Although it will undoubtedly give me figures to work with it seems like more of a ballpark than real world figures.

There are great arguments for and againt I guess. Perhaps I will wait a while longer, I've ridden for many years without power so it's hardly an issue at this point. Maybe I could hold out for the Garmin Rally to come down in price a bit (not any time soon) or save a while longer.