would like a new powermeter

Discussion in 'Power Training' started by Mac_Biker, Jun 8, 2013.

  1. Mac_Biker

    Mac_Biker New Member

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    I currently have a wired powertap on a mavic open pro rim, on my "trainer bike". That bike only rides on the trainer, because I've sweated so much into the headset that it's stiff now.

    I ride a Cannondale Supersix Hi-MOD with campy chorus 11 speed.

    I would like to get a wireless powermeter for the bike. I was thinking of either going with a new wheelset with a power tap. Something like these from performance bike: http://www.performancebike.com/bikes/Product_10052_10551_1147608_-1___000000

    I would like have to get a campy free hub body to switch out.

    Another route I was looking into is getting a quarq or the new crank arm from stages cycling. I would love the flexibility of changing wheels and still keeping the powermeter. But I'm not very familiar with it. I have a campy setup, so I'm not sure where to start. And I would have to lose my campy crank, not sure how much I can get for it on ebay. What quarq or stages power meter would I get for my bike?

    I have a BB30 for the bottom bracket.
     
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  2. alienator

    alienator Well-Known Member

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  3. Mac_Biker

    Mac_Biker New Member

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    I've also considered waiting for the garmin vector or brim brothers pedal / cleat based power meter. Just not sure if I want to wait another <sarcasm>5-10</sarcasm> years before we can get one...
     
  4. danfoz

    danfoz Well-Known Member

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    I have not heard great things about the consistency of the Stages PM. I had high hopes for the Vector, looks like we'll be waiting a little longer.
     
  5. daveryanwyoming

    daveryanwyoming Well-Known Member

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    Stages definitely seems to be having issues with their accelerometer based cadence measurement which leads to problems with estimating angular velocity and power. But even if they resolve those issues it's still a one sided measurement meter like Ergomo that is based on the assumption that a rider's total power is always double the power generated via the left leg. There's a lot of research that suggests this in general is not true and that individual leg contributions to total power change not only between riders but for a given rider vary based on riding intensity and vary day to day.

    So even if they work out their cadence stability issues you'll still get a PM with a random time varying error with the magnitude of that error depending on your particular left to right leg imbalance and how it changes in different situations. Of course you won't know how much or how little error you have unless you run a more conventional PM at the same time for comparison.

    That was the situation with the Ergomo that I used for a few months as my first PM. When I contacted their customer service after getting some crazy high and low power readings on some rides they actually told me to find a friend with a PT wheelset, borrow the PT and do a comparison to find out if the Ergomo actually had an error. I was kind of blown away by that answer, borrow our competitor's product to find out if our product actually works... I don't see how it will be any better with Stages, the numbers may or may not seem stable and repeatable but unless you run a conventional meter that can be torque tested and has known accurate cadence (angular velocity) measurement and does not rely on the 50/50 left to right leg balance assumption you'll never know if the numbers you see are valid or not.

    No doubt many will go with the Stages as a low cost way to start training with power. No doubt many will be happy as long as the numbers seem reasonable and as long as they don't ask too many questions about accuracy or want to do things like aero field testing just as many today are content with Strava's power estimations. But if you actually want accurate power numbers I wouldn't go with Stages.

    -Dave
     
  6. ambal

    ambal Active Member

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    Stages crank based PM is cheap if you're happy with the 105 cranks and already own a garmin.
     
  7. steve

    steve Administrator
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    You would think garmin would have no trouble getting the technology to work.
     
  8. joroshiba

    joroshiba New Member

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    Well their edge series still doesn't seem to work properly in terms of power data handling and not breaking (I'm on my 3rd edge in 3 months)
     
  9. alienator

    alienator Well-Known Member

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    Garmin has acknowledged some QC issues, and QC is one reason why the Vector hasn't been released yet. Garmin has stated they want to be sure that Vector power readings are precise. I don't think pedal axle based power measurement is as easy as it might have seemed. Look/Polar have had issues with their power meter, and I'd wager that they were working on that power meter for quite a while before said work became public. MetriGear's work may not have been as far along as Garmin thought or as far along as it should have been. No matter the reasons, it is difficult to justify buying a Look/Polar unit or (when they come out) a Garmin Vector set given their prices compared to those of current power meters. Moreover, it's not certain that the abilities that pedal based power meters bring (namely, measuring individual leg power or force vector) are really meaningful. Time and studies will tell on that point. If someone is interested in those parameters (at least measuring individual leg power), Rotor's power meter is an option.
     
  10. baker3

    baker3 New Member

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    As with everything, more competition is good for customers, these look good: http://www.stagescycling.com/stagespower

    • ±2% accuracy of strain gage measured power
    • Super light fully sealed unit adds just 20g of additional weight to the crank arm
    • Designed and approved for Road, Tri, MTB, DH, cyclo-cross, BMX and Track.
    • Bilingual communication with ANT+[SIZE= small]â„¢*[/SIZE] and Bluetooth Smart** protocols
    • Internal sensor based cadence measurement — no magnets needed
    • Active temperature compensation
    • Wireless firmware upgrades
    • Simple zero reset
    • Fast set up: install crank arm, pair, and go
    • No wires, magnets, zip-ties, or additional mounted hardware
    • Left arm only design, means no compromise on drive-side spider stiffness or chainrings
    • 1-year warranty against manufacturing defects
    • Optional 2-year accidental damage protection; Stages Cycling PMP (power meter protection) plan
    • Designed and assembled in Boulder, CO USA
     
  11. bmoberg337

    bmoberg337 Member

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    [SIZE= medium]I have been using the stages powermeter since January and overall have been very pleased with it. Prior to using the stages powermeter I was using the cycleops powertap SL. There was actually very good correlation between the power readouts between the two powermeters so I had confidence in what I was getting with the stages pm. However, I did have some issues with the stages pm that were resolved very quickly. [/SIZE]

    [SIZE= medium]The first problem happened after having the pm for only a month. The pm readouts were way off (it was reading 1000+watts when I was pedaling easy). This was not resolved by calibrating the unit or replacing the battery. I called stages and I had a new pm on my doorstep the next day no questions asked. The next unit worked for about a month and the cpu that is mounted via an adhesive on the inside of the crank fell off. Stages admitted that they were having issues with a batch of units that got bad adhesive, and again overnighted another pm to me. I have had the third unit for about two months now with no issues and hope it will stay that way. Like all new things, there are some bugs to work out, but the people at stages definitely make customer service a top priority so in my opinion its worth your money.[/SIZE]

    [SIZE= 11pt]Also, I have seen a lot talk regarding the accuracy of the stages pm because it is only taking power measurements from one side. Unless you need to consistently keep comparing data from different pm units I don't understand why a high level of accuracy is needed from any pm in training. What really matters is the consistency in pm readings from a given device. I do not notice any huge fluctuations in pm readouts on the stages unit, and in my opinion is just as consistent as the powertap . [/SIZE]
     
  12. Alex Simmons

    Alex Simmons Member

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    How much accuracy matters depends on the use for which you intend the power meter.

    If you are looking for a device to provide some overall guidance on training loads, an indicator that you are at the right level when training, for detecting reasonable sizeable fitness gains, then a high degree of accuracy is less critical as these are not particularly demanding uses of power meter data. And that may well be the extent of the need for many people.

    The left-leg only issue is not one that will be consistent for everyone, and so while the measurement may well be accurate for the left side, the overall power measurement accuracy will not be the same for everyone.

    There are other uses for power meter data for which this would be inadequate level of accuracy. These include, inter alia:

    Maximal force - velocity testing and analyses derived from this
    Aerodynamic field testing with the precision of a (good) wind tunnel
    Finer levels of fitness assessment (which is what you want to assess after a few years when fitness changes occur in far smaller increments)

    I have not decided on sensitivity to some other applications such as pacing strategy and analysis, but when in doubt, I err on the side of known accuracy.
     
  13. ambal

    ambal Active Member

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    It all comes back to cost and the reason a person has for needing/wanting a powermeter
     
  14. danfoz

    danfoz Well-Known Member

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    Just installed.

    the PM, BOR688 crank, and BB came in just under $1700 incl/shipping.

    Customer service was good and I got a very quick post sale email w/some questions. Arrived less than a week after ordering. I wouldn't hesitate recommending based on my experience so far.

    Running Athena11. The BOR 10/11 chainrings ride smooth and shift well.

    [​IMG]
     
  15. alienator

    alienator Well-Known Member

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    Nice. People looking for power meters would be wise to give a second consideration to PowerTap since they just dropped their prices by about $500, at least on their G3 hub. They've dropped prices on their wheels, too.
     
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