Ergomo Pro or Power Tap SL 2.4?

Discussion in 'Power Training' started by Mooter, Apr 15, 2007.

  1. Mooter

    Mooter New Member

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    Taking the price out of the equation. Which power meter should I purchase? I will admit that I'm leaning toward the Ergomo because I can use any type of wheels. I also live near the mountains and at altitude and the included altimeter would be nice.
     
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  2. Woofer

    Woofer New Member

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    How many bikes do you own and how much do you ride them? (how much trouble/is it possible to swap between them if you decide to do that, what cranks/bb are on them, etc)

    How important is it to for you to be able to check the accuracy of your system?

    Which one do your friends own? This helps when you need to troubleshoot if you don't have the luxury of multiples of one type of system.

    Where do you live? Graber's service center is in Wisconsin. Ergomo's is in Germany.
     
  3. vadiver

    vadiver New Member

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    If you are taking price out of the equations why not the SRM or multiple wheels for the PT?

    It sounds like you still have price in the equation, that makes it harder to analyze.
     
  4. Ergoman

    Ergoman New Member

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    I've never used a PT or SRM, so I can't speak to their pros and cons other than to observe that the PT with a wheel costs about the same as an Ergomo, and that the SRM is much more expensive. The new Polar CS600 is attractively priced and may be a realistic alternative, but the jury is still out since it has just recently become available. The iBike is reported to be little more than a toy. I do own an Ergomo and have given it extensive use and testing.

    Ergomo Pros:
    Excellent software (version of Cycling Peaks WKO)
    Displays TSS and IF on Pro Power screen
    Displays altitude and temperature, displays %grade
    Very good user interface in general, excellent interval mode
    Easy to keep charged, only one batttery that's good for about 10 hrs
    Huge memory capacity, can record 11+ hrs at 1 sec intervals
    Can use any wheels and any crankset you want
    Clean installation, hard wired but unobtrusive. No dropouts or interference.
    Factory calibrated, and easy to check accuracy with offset procedure
    K-factor adjustment allows for matching to other power meters and consistency with previously recorded data

    Ergomo Cons:
    Installation is critical and must be done correctly
    U.S. Distrubuter located in Charlotte, N.C. is slow to respond
    User manual is weak
    Offset is very temperature sensitive, must be checked every ride
    Difficult to move from bike to bike

    It is a misconception that the Ergomo can't be user tested and set for accuracy. The BB unit is calibrated at the factory and the calibration is certified by an independent lab. With the exception of a catastrophic mechanical failure of the unit, this calibration will always be more accurate than hanging weights from a pedal as some other power meters require. Running a simple (20 second) offset procedure before every ride allows the user to verify accuracy.

    The Ergomo measures spindle twist to determine power, and since the spindle is mostly twisted by force on the left crank, some argue that Ergomo power readings are inaccurate for those with one leg stronger than the other. I can only speak from my experience, and after testing for many miles on different calibrated trainers, I've determined that the whole leg imbalance thing is a non-issue.

    Minor quirks: When the backlight is used, power readings are displayed 20 watts low. Air temperature display is inaccurate in direct sunlight. Circular plugs are a pain to align.

    My biggest complaint with the Ergomo is it's sensitivity to temperature. It may be my installation, or it may be that all installations are temperature sensitive. The only other problem I had was with customer service. The computer unit on my Ergomo failed and I returned it under warranty to the Distributer (Gita Bike) in Charlotte, N.C. I expected a two or three day turn-around, but it took almost two weeks. Communication was very poor, and none of my phone calls were ever returned. In any case, given all the trade-offs among power meters, I'd still buy the Ergomo again, particularly if I lived in a mountainous area.

    Disclaimer: I am not employed by Ergomo, and have no financial interest. I have nothing to sell to anyone reading this post. I'm here to share what I know and to learn.
     
  5. peterpen

    peterpen New Member

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    A few quibbles:
    Hmm, this is simply not true, as shown by numerous posts to the Wattage group among other accounts. Per user reports, even brand new, properly installed Ergomos can and do read incorrectly. Of course, you have no way of knowing this without another powermeter.

    The fact that the Ergomo only measures power from one leg may not be an issue for you, it could be for the OP. Or it might not be for the OP, unless the ride is longer than 3 hours. Who knows?

    Ergomos can not be used with "any crankset." Must be square taper, ISIS, or Octalink, an increasingly short list.

    I think Woofer's questions are good ones to for the OP to consider. Even with the wheel limitation, I'd go for the PowerTap. The 2.4 still has growing pains, but a PT SL with a light, strong build (CX-Rays or Revolutions, Cadence Aero or Velocity Aerohead rim) is a great power choice for training and racing.
     
  6. TamMan

    TamMan New Member

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    I have both devices. Here are my thoughts:

    Ergomo: - Awesome computer...the best display around
    - Stable connection (in comparison to wireless)
    - NP, IF, TSS available
    - Difficult to install correctly...and you aaaalways wonder...
    - Ability to charge computer and to travel with it (adaptors are included)

    PT 2.4: - Crappy computer
    - Quality issues (had to send mine back once already)
    - Batteries drain like crazy (4-5 rides - it's getting expensive)
    - Dropped signals on pretty much every ride depending on where you are

    Good luck - I really like both but prefer the Ergomo simply because it is a super display. But again...you always wonder (probably because of all the discussions).
     
  7. acoggan

    acoggan Member

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    Sorry, but I disagree. First, as Ergomo's own installation instructions demonstrate, just because the accuracy of the sensor is certified prior to shipment doesn't necessarily mean that it will still be accurate once it's installed in a bike. Second, even if how it is installed doesn't impact the calibration, there's still the whole right/left balance issue (as you mention below).

    For you, maybe, but possibly not by others. Indeed, based on the few published scientific studies on the topic, a R/L imbalance of up to 10% seems to be the rule, rather than the exception.
     
  8. Ergoman

    Ergoman New Member

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    The vast majority of online complaints about Ergomo accuracy come from folks who quite obviously haven't done a proper installation and/or don't understand the importance of frequently checking offset (or don't even own an Ergomo and just want to play expert). With the Ergomo, after checking offset, simply spinning the pedals under no-load and observing the left/right power readings will quickly tell if the power reading is correct. In any case using one power meter to check another is like measuring your height by standing next to someone who doesn't know his own height.

    If there is a leg imbalance and if the Ergomo algorithm does not correctly accomodate it, and if it can't be adjusted for with the K-factor setting, and if, as a rider tires, the ratio of the imbalance changes, and if the rider rides long enough for this fluctuating imbalance to become a factor, then there may be an error in the absolute values reported by the Ergomo. That's a long list of "ifs", and the fact of the matter is that absolute accuracy in power isn't nearly as important as consistent relative readings, which the Ergomo would continue to supply.

    Finally, you are correct. Ergomo can't be used with any external bearing crankset. If I were to purchase a new Ergomo and if I didn't already have an ISIS, Octalink or square taper crankset, I would probably get the square taper crankset that Ergomo sells, or for about $180 on eBay you could find an FSA Carbon Team Issue for ISIS, which is one of the nicest cranksets recently made.
     
  9. peterwright

    peterwright New Member

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    I have been trialling an Ergomo for the last 1000km alongside my regular calibrated PT SL's.

    I run a power based coaching business and have been looking at offering Ergomo.

    In short - I have been unable to get the Ergomo to track the PT in a linear fashion despite numerous K Factor tweaks. Offset is steady, but I can either achieve tracking at power >FTP or at power <FTP but not both.
    Differential is as much as 28w in a race with an NP of 256w - so pretty significant (and is generally ~10-12%)

    Temperature change is minimal and offset steady both pre and after rides.

    I am not aware of, nor do I think I have any leg imbalance at lower power levels. I have taken great care and worked with the local agent to ensure a 100% to spec installation and am happy this is correct.

    The bottom line is that despite a great interface and excellent functionality, I find myself unable to recommend this device due to it's inability to track a calibrated benchmark ( three X PT & computrainer in this case)

    I have now got three clients using Ergomo and all have problems obtaining consistency with the device.
     
  10. oettam20

    oettam20 New Member

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    The same for me.
    I'ma an Ergomo user and I have the same problem of consistency with the device.
     
  11. Ergoman

    Ergoman New Member

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    In the book which you co-authored, you wrote:

    "Every rider has a small discrepancy in leg strength, but for the majority of people, this discrepancy is less than 5 percent;"

    What changed?

    You went on to write:

    "If a rider does not have a large discrepancy in leg strength - from and injury, for example - then the ergomo can be adjusted to provide the rider with a very accurate picture of his or her wattage."

    Do you no longer believe this to be true?
     
  12. acoggan

    acoggan Member

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    Nothing. I didn't write that part of the book (nor do Hunter and I necessarily see eye-to-eye on every other thing that's in there).

    I never did.
     
  13. Ergoman

    Ergoman New Member

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    Hunter thinks the Ergomo is OK and you don't? Who are we to believe?
     
  14. acoggan

    acoggan Member

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    Me, of course (right, Hunter? ;)). :D
     
  15. peterpen

    peterpen New Member

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    Beg to differ. What you describe with the Ergomo will simply let you know if the power reading looks or doesn't look right - not if it is correct. When I zero the offset on my SRM, just because those numbers match doesn't mean that the power reading is correct. It is the ability to check (and change) the slope that lets me know the power reading is correct.

    And using one power meter to check another is perfectly valid - if the PM of reference is a PowerTap or a SRM, both of which can have their calibration verified with accurate weights.

    In any case, to the OP - at this point neither the Ergomo nor the SL 2.4 seem to be a solid choice. In that price range I'd recommend a wired PT SL or a used SRM amateur.
     
  16. nrhorwitz

    nrhorwitz New Member

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    Not attempting to discredit you. My experience has been different with Gita Bike and Nelson Frazier. He's been quick in answering my emails and helping out the customers I work with regarding Ergomo. I've been happy with his support.
     
  17. johnb263

    johnb263 New Member

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    By Ergomo (Germany's) own admission, adjusting the k-factor alters the linearity of the unit's power reading... I've got a email reply as evidence.
     
  18. Ergoman

    Ergoman New Member

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    Your experience may have been different from mine for many reasons. It may be that you do a lot more business with Gita Bike.

    The fact remains that it took a full two weeks for Gita Bike to turn around a failed computer unit. I live just a few hundred miles away, I used Priority Mail and the mail takes one day. There were no intervening holidays. I made numerous calls in an attempt to confirm status of my warranty work, and none were returned. Worse yet, on the few instances when a real person answered, the response was "I don't know, I'll find out and call you right back." No one ever called back.
     
  19. Ergoman

    Ergoman New Member

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    How much inaccuracy is introduced in hanging weights to do a calibration? How accurate is the weight? If you weigh it, how accurate is the scale? How close to level is the crank arm? How accurate is the measurement of the lever arm? How accurately is the weight placed? It wouldn't be too hard to introduce a 2% error in each of these steps. The product of all those errors could be significant. My point is that absolute accuracy is a very hard thing to attain, even in a lab. Finally, once you do all this weight hanging and testing, there's still the issue of how each meter measures, processes and records data.

    It's impossible to attain absolute accuracy from a power meter...any power meter which is why it doesn't make much sense to judge the output of one by comparing it to another, particularly when the differences are small. Fortunately, consistent results are what's important. With the exception of sensitivity to temperature (which can be overcome by paying close attention to offset), the Ergomo has been very consistent for me. YMMV.
     
  20. vadiver

    vadiver New Member

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    I do many rides where I start out early in the morning when the Air temp is in the low to mid 70s F and return when the temp is in the mid to upper 90s. (my guess is the road temp ranges from low 70s to 110 or so just under the BB) How does this teperature affect the readings.
     
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