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Stages Single Side vs Dual Side Power
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A friend asked me to look into the Stages power meter for him but I don’t have any experience with it. I use the Vector 2 pedals with no issues but his budget is $500 max so kind of limited. Does he really need the dual sided or go w the single side for $400 on Amazon right now? Would it be worth it to hold out for a better deal on any power meter dual sided for around $500? Is that even possible?

Thanks!
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Re: Stages Single Side vs Dual Side Power [mbecks2] [ In reply to ]
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Too bad he didn't snag the Vector 2 last weekend @ $549. Personally I think single sided is fine. I'm fairly constant at 48/52 so as long as it doesn't change much more than a %, he should be fine for single sided.
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Re: Stages Single Side vs Dual Side Power [mbecks2] [ In reply to ]
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mbecks2 wrote:
Would it be worth it to hold out for a better deal on any power meter dual sided for around $500? Is that even possible
The closest it'll get for him will be the Favero. Or a spider-type solution that by itself is already around that price.
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Re: Stages Single Side vs Dual Side Power [mbecks2] [ In reply to ]
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Power2max starts at $500. Spider based so measures both sides.

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Re: Stages Single Side vs Dual Side Power [mbecks2] [ In reply to ]
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With the availability and pricing of dual or aggregate power meters, there is really no reason to settle for a power estimator anymore. As Jason said, Power2Max is a good option at $500. Or a used quarq.
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Re: Stages Single Side vs Dual Side Power [mbecks2] [ In reply to ]
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The downside to single-sided power is consistent inaccuracy. It is like a broken analog watch-- it is correct twice per day, but just don't know when those moments occur. If he has a power imbalance, then the power will be incorrect by about 2x the % off. For example, if his L/R imbalance is 48%/52%, then the PM would read about 4% low. For example, if he was riding at 250W with a 48/52 imbalance, the PM would read 240W. At least it would be consistent, as long as his imbalance was consistent.
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Re: Stages Single Side vs Dual Side Power [mbecks2] [ In reply to ]
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mbecks2 wrote:
A friend asked me to look into the Stages power meter for him but I don’t have any experience with it. I use the Vector 2 pedals with no issues but his budget is $500 max so kind of limited. Does he really need the dual sided or go w the single side for $400 on Amazon right now? Would it be worth it to hold out for a better deal on any power meter dual sided for around $500? Is that even possible?

Thanks!

I didn't see the Amazon deal, but if it's for the Ultegra 6800, you can find better deals than that... I got one for slightly less than 300$ recently - I didn't get into details, but I think they are clearing them out for a newer version of Ultegra?
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Re: Stages Single Side vs Dual Side Power [mbecks2] [ In reply to ]
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if you really have a choice, go dual sided as it eliminates some potential error and really eliminates wondering if it makes a difference, which is actually worth some money. But, I have some friends who have had great success racing bikes who have used Stages single sided power meters for power training. Most of them got their Stages 5 years ago instead of waiting for dual sided power meters to drop below $1600. The moral of the story is any power meter you can put on your bike today is a million times better than the perfect power meter you might be able to afford in the future ;-) Frankly, I got a Quarq 2 years ago and I love it, but I'd probably be a better cyclist today if I had bitten the bullet and bought a Stages 4 or 5 years ago.

If you friend can swing a dual sided PM in the next month or so, wait. If it is going to be a next summer kind of thing, he will be way better off training this winter on a one side PM than with no PM.
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Re: Stages Single Side vs Dual Side Power [STP] [ In reply to ]
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Have a look at the FSA Powerbox, at $596 I think it makes absolutely no sense to pick up a single sided stages.

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Re: Stages Single Side vs Dual Side Power [exxxviii] [ In reply to ]
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exxxviii wrote:
The downside to single-sided power is consistent inaccuracy. It is like a broken analog watch-- it is correct twice per day, but just don't know when those moments occur. If he has a power imbalance, then the power will be incorrect by about 2x the % off. For example, if his L/R imbalance is 48%/52%, then the PM would read about 4% low. For example, if he was riding at 250W with a 48/52 imbalance, the PM would read 240W. At least it would be consistent, as long as his imbalance was consistent.

That's not strictly true. The 2% refers to the range of accuracy, not how inaccurate the power meter is. So the reading could be anywhere between 2% low or 2% high. It could be absolutely spot on. So using the example above, the left handed power meter is reading the left leg at 120watts and doubling it to 240. 2% either way means that the actual power being put out by the left leg is anywhere between 117.5 watts and 122.5 watts. This then means that the overall reading could be anywhere between 235 watts and 245 watts. If the 48/50 is consistent at all powers then that reading is as accurate as a double sided power meter as the left leg will always be putting out 48% of the overall power and the power meter will give this reading, +/- 2% (which is the same level of accuracy as almost all power meters out there).

That's the issue with single sided, it's whether any imbalance is consistent across all power ranges. The only way to tell is with a TRUE double sided power meter (such as power tap P1 or Garmin Vectors). SRM is not a true double sided power meter, for example. So, you could spend a chunk of money on a true double sided power meter to find that your leg balance is consistent across all power levels. End result, your readings from a single sided power meter will be just as accurate (save for silly situations where you deliberately pedal harder with one leg, or do single leg drills) as a double. Single sided are a compromise and, for some people, not particularly accurate. For many, however, they work almost as well, if not as well as, a true dual sided power meter.

I have no vested interest. I started on a stages and using a stages I improved my FTP by around 25% from when I first bought it. I now own power tap P1s and they give me the same FTP readings as my stages and I've found the only time I am biased is high power, high torque (i.e. climbing a 20%+ gradient). Any other time, I am 50/50. The end result, I could have kept my stages and it would have served me perfectly.
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Re: Stages Single Side vs Dual Side Power [exxxviii] [ In reply to ]
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exxxviii wrote:
The downside to single-sided power is consistent inaccuracy. It is like a broken analog watch-- it is correct twice per day, but just don't know when those moments occur. If he has a power imbalance, then the power will be incorrect by about 2x the % off. For example, if his L/R imbalance is 48%/52%, then the PM would read about 4% low. For example, if he was riding at 250W with a 48/52 imbalance, the PM would read 240W. At least it would be consistent, as long as his imbalance was consistent.

Except most people do not have a consistent imbalance. Most people will have a balance that varies with length of ride, power zone, and other variables.
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Re: Stages Single Side vs Dual Side Power [trener1] [ In reply to ]
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trener1 wrote:
Have a look at the FSA Powerbox, at $596 I think it makes absolutely no sense to pick up a single sided stages.


Agreed, with a caveat. If you really do only have $399 and coming up with $596 (at Christmas time no less . . .) is going to delay you for a couple months one should give very serious thought to pulling the trigger now on the Stages. Not everyone can just snap their fingers and increase their budget by 50%.

You'll get more out of training with a Stages in December, January and February than you will out of having no PM then getting a dual sided one in March.
Last edited by: STP: Nov 30, 17 7:42
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Re: Stages Single Side vs Dual Side Power [lordhong] [ In reply to ]
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lordhong wrote:
but I think they are clearing them out for a newer version of Ultegra?
Yes, R8000.
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Re: Stages Single Side vs Dual Side Power [STP] [ In reply to ]
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Yeah you are 100% right.
My comment was based on the OP saying that budget was $500, figured $596 isn't that much of a stretch and you get so much more.
But yes at $399, that's a bigger stretch.


STP wrote:
trener1 wrote:
Have a look at the FSA Powerbox, at $596 I think it makes absolutely no sense to pick up a single sided stages.


Agreed, with a caveat. If you really do only have $399 and coming up with $596 (at Christmas time no less . . .) is going to delay you for a couple months one should give very serious thought to pulling the trigger now on the Stages. Not everyone can just snap their fingers and increase their budget by 50%.

You'll get more out of training with a Stages in December, January and February than you will out of having no PM then getting a dual sided one in March.
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Re: Stages Single Side vs Dual Side Power [lbmxj560] [ In reply to ]
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lbmxj560 wrote:
That's not strictly true. The 2% refers to the range of accuracy, not how inaccurate the power meter is.

You are combining multiple things... measurement inaccuracy is independent of inaccuracy caused by a user's power imbalance. The manufacture's accuracy rating does not take into account inaccuracies that a user might contribute. Here is a quick illustration to show how a 48/52 power imbalance would result in a 4% error that is entirely unrelated to the unit's accuracy range for a simple measurement:

Left Power: 120W (48%)
Right Power: 130W (52%)
Actual Power: 250W

Stages 1-Sided Power: 240W -4% error (2x L Power)

That left power 120W reading also has a ±2% error range, so the user's actual power could be in the range of 118W - 122W.

It does not matter that imbalance may change during the workout. It introduces yet another variance on top of the inherent accuracy of the measurement itself.

If you add it all up, you might be producing 255W, but the unit might read 240W. Or not. The errors are cumulative. In this example, a single-sided unit has an error range something like ±6%. That is why a unit with total power (like crank, pedals, or a hub) are more likely to be closer to reality than a single-sided meter.
chaparral wrote:
Except most people do not have a consistent imbalance. Most people will have a balance that varies with length of ride, power zone, and other variables.
Yes, and this multiplies the inaccuracies of single-sided meters.
Last edited by: exxxviii: Nov 30, 17 8:17
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Re: Stages Single Side vs Dual Side Power [mbecks2] [ In reply to ]
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My n=1

I bought a close-out Stages one-sided PM for my P2 and pair it with my Garmin 510.

With the exception of 2 battery changes, it's worked flawlessly through the last 1.5 yrs (3 HIMs and 1 IM).

YMMV....but, I wouldn't hesitate to buy another one (and may for my roadie).

Good luck.
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Re: Stages Single Side vs Dual Side Power [nc452010] [ In reply to ]
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As an FYI
Just saw that Power Tap is running some specials.
They have refurbished wheelsets and pedals at $549.
Seems like a crazy smokin deal.
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Re: Stages Single Side vs Dual Side Power [mbecks2] [ In reply to ]
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I had 2 sided before I had one sided...largely because I was curious post left knee surgery. I normally see 50/50 occasionally 48/52 at worse. The more climbing I do typically all 50/50.

Using Vector2 and Stages v1.... just got Vector3.. so that will be going on the road bike.. V2 will be going on the TT bike and the stages will be going back to the wife's bike. For me I dont have an issue with one side because I dont do the type of workouts where dual is needed or something better then stages is required.
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Re: Stages Single Side vs Dual Side Power [mbecks2] [ In reply to ]
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PowerTap C1 @ $349. Basically a no-brainer at this price point.

https://www.powertap.com/...amp;utm_medium=email

The point is, ladies and gentleman, that speed, for lack of a better word, is good. Speed is right, Speed works. Speed clarifies, cuts through, and captures the essence of the evolutionary spirit.
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Re: Stages Single Side vs Dual Side Power [Toby] [ In reply to ]
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Toby wrote:
PowerTap C1 @ $349. Basically a no-brainer at this price point.

https://www.powertap.com/...amp;utm_medium=email

I'm too superficial to run those rings :)
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Re: Stages Single Side vs Dual Side Power [mbecks2] [ In reply to ]
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The greatest value of training with power is the objective measure of effort and a single-side power meter can do that just fine.

My latest Quarq DZero offers R/L metrics - I've looked at them once or twice and didn't see anything particularly interesting and continue to just look at the Averaged/combined figure to gauge my efforts. Of course more features is 'better' but if you're shopping on a budget I would say L/R metrics are a ways back on the list of priorities. After all - we rode with a single watt figure for ~ 10 years once power meters became commonplace.

If you're an aspiring pro, or maybe have some injury history the priorities might change - but for a typical age grouper, single side power will be helpful over no power.

" I take my gear out of my car and put my bike together. Tourists and locals are watching from sidewalk cafes. Non-racers. The emptiness of of their lives shocks me. "
(opening lines from Tim Krabbe's The Rider , 1978
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Re: Stages Single Side vs Dual Side Power [TriDevilDog] [ In reply to ]
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TriDevilDog wrote:
The greatest value of training with power is the objective measure of effort and a single-side power meter can do that just fine.

My latest Quarq DZero offers R/L metrics - I've looked at them once or twice and didn't see anything particularly interesting and continue to just look at the Averaged/combined figure to gauge my efforts. Of course more features is 'better' but if you're shopping on a budget I would say L/R metrics are a ways back on the list of priorities. After all - we rode with a single watt figure for ~ 10 years once power meters became commonplace.

If you're an aspiring pro, or maybe have some injury history the priorities might change - but for a typical age grouper, single side power will be helpful over no power.

You seem to be confusing power meters that only measure the power of one leg with those that measure that of both combined.

As someone else pointed out upthread, the error of the former is equal to the technological error PLUS twice the variation in L-R balance. The latter in turn is not necessarily constant, but can vary based on exercise intensity, cadence, fatigue, etc. Net-net, such devices really aren't worth much, especially for a triathlete who is presumably most interested in their performance over longer durations, in which, e.g., heart rate can be a reasonable indicator of intensity.

OTOH, unless you are attempting to diagnose or rehabilitate an injury, I don't really see any use case to be made for power meters that measure and report the power of both legs separately.

(Then there is your Quarq, which can only pretend to differentiate between the contributions of your two legs... that's a "feature" that can be worse than what you pay for it even it is free.)
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Re: Stages Single Side vs Dual Side Power [Andrew Coggan] [ In reply to ]
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Far be it from me to argue with the guy who wrote the book on it!

Thanks for the clarification Andrew
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Re: Stages Single Side vs Dual Side Power [TriDevilDog] [ In reply to ]
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TriDevilDog wrote:
Far be it from me to argue with the guy who wrote the book on it!

Thanks for the clarification Andrew

In fairness (and upon review), it was really only your first sentence that threw me. Otherwise we said essentially the same thing.
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Re: Stages Single Side vs Dual Side Power [mbecks2] [ In reply to ]
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Using the pseudo L/R balance reading's from my Quarq, just in the last week I've seen differences of up to 2.6% in my left leg power. So potentially a 5.2% difference in what a single sided power meter would report. None of my rides in the last week have had the same L/R balance, and there isn't any consistency to help account for those differences.

I don't see the point in spending money to buy a tool that is meant to accurately track your training and fitness (among other things where accuracy is important) when you never know when it's accurate and when it isn't. Unless of course you've done extensive testing on yourself and can anticipate your L/R balance and it's potential fluctuations...but you'd need to ride A LOT with dual sided PM to do that first to even know if it's possible.
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