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Thread: Friction and Watts

  1. #1

    Default Friction and Watts

    Hi,
    I read this on this review on the CycleOps site.Is this a bit of an exaggeration?
    CycleOps did not respond to the claim.

    My biggest beef with the Pro300PT is that it will not hold a constant resistance level. If you dial in a specific resistance and expect to train at that level, forget it. The resistance pads begin to heat up and expand, increasing the level of resistance without any adjustment on your part. It would be okay if this were a minor issue, but I've seen increases of +50% (in watts) over the course of a 30-40 minute workout.
    On a related note,is anyone familiar with the PowerCal?

    Introducing CycleOps PowerCal, the worlds' first-ever power meter calculated from heart rate. ANT+ compatible, simple to set up and easy to use. Includes CycleOps Speed Sensor, which can be configured to detect speed or cadence.

  2. Default

    I can't speak specifically to the CycleOps bike, but I have definitely experienced the phenomenon described on other bikes using a friction braking system (but on bikes with no consoles, so can't really quantify how much the resistance increases).

    PowerCal isn't really a power meter.... It's basically a heart rate monitor that uses an algorithm to try and translate heart rate to power. I haven't used it, but it seems to me it wouldn't be that much more useful than just training by heart rate zone. It certainly wouldn't respond as quickly as a "real" power meter for short, high intensity bursts of power.

  3. #3
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    Quote Originally Posted by taowave View Post
    I read this on this review on the CycleOps site.Is this a bit of an exaggeration?
    Personally I don't know if this could be considered a big deal or not. Other than in the past when I was trying to do an isopower workout on my own bike without a power meter, I can't think of a time when I didn't make adjustments to the resistance knob.

  4. #4
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    Quote Originally Posted by InnerDrive View Post
    PowerCal isn't really a power meter.... It's basically a heart rate monitor that uses an algorithm to try and translate heart rate to power. I haven't used it, but it seems to me it wouldn't be that much more useful than just training by heart rate zone. It certainly wouldn't respond as quickly as a "real" power meter for short, high intensity bursts of power.
    For what it's worth, a few years back I compared actual TSS (from power meter data) to an estimated TSS based on HR reserve. For those who are familiar with statistics, I found an R^2 of about 0.6. My conclusion was that I could estimate TSS just as (if not more) accurately using RPE than I could with HR. I therefore question the value of PowerCal. That said, like a HR based calorie counter, I can see its appeal for those who love numbers without the knowledge to question their number's validity.

  5. #5

    Default

    Reading from CycleOps site:
    Introducing CycleOps PowerCal, the world's first-ever power meter calculated from heart rate. For years there has been a widely recognized correlation between power and heart rate. In a lab one can predict power output or intensity by knowing heart rate, and vice versa....

    But if it is based on Heart Rate, it may be that also the Cardiac Drift doesn't help to be "near accurate".

    :-) Ciao Matteo

  6. #6
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    Default

    Quote Originally Posted by matteobma View Post
    Reading from CycleOps site:
    Introducing CycleOps PowerCal, the world's first-ever power meter calculated from heart rate. For years there has been a widely recognized correlation between power and heart rate. In a lab one can predict power output or intensity by knowing heart rate, and vice versa....

    But if it is based on Heart Rate, it may be that also the Cardiac Drift doesn't help to be "near accurate".

    :-) Ciao Matteo
    Or that a seriously deconditioned athlete can be applying a whopping 100 Watts to the apparatus and sucking wind whereas a Performance Machine can be barely breaking a sweat at double that......add a multiplyer of cardiac drift PLUS an axe murderer busting into the cycle studio and threatening to hold everyone hostage and I could see the potential for burning more Calories than anyone could ever consume in a day.

    I did my CycleOps cert up in Montpelier, Vermont with Joey Adams and a few boys from the Onion River Cycling club......some serious wattage was generated there. Per my HR, I'll wager I got the best Calorie burn driving home.....a 6 hour +, white knuckle drive thanks to a freak snowstorm (not that I would've been gaping at my HRM, mind!)

    Vivienne

  7. #7

    Default IR thermometer

    One of my class suggested getting an infra-red thermometer as a way of telling how hard members of the class are working. the bikes we have have the large steel wheels on the front, and they get hotter the more resistance and the harder you pedal. There must be a relationship to power here?

  8. #8
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    Quote Originally Posted by Jonnyspin View Post
    One of my class suggested getting an infra-red thermometer as a way of telling how hard members of the class are working. the bikes we have have the large steel wheels on the front, and they get hotter the more resistance and the harder you pedal. There must be a relationship to power here?
    Well, it'll tell you something about the temp. of the flywheel......which might be relevant to how tight the brake pads squeezed it/pedal speed etc. for as long as it took to get to that temperature before the infra red gizmo was applied (which may or may not be no more than 5 minutes, for all I know) Or not.

    I can't see how this would give any worthwhile feedback to the individual riding the bike if they're wondering how hard they should be working in order to match the cues you're giving. Jeebus.....if someone measured the temp of my flywheel when I did my CycleOps cert up in Vermont with Joey Adams and a few dudes from the Onion River Racing team, I can't imagine how "cool" I would've looked next to 360 Watt Phil (he had to stop his graded power output assessment when his wife and kids appeared to say *Hi*......and I was sitting on the floor!)

    Seems to me that the more sophisticated the measuring device is, the less relevance the numbers have to what it is you need to know.

    **But seeing as you've got *the numbers* there in front of you on a CycleOps bike.....why would you even contemplate another measurment device?

    Vivienne
    Last edited by Vivienne; 10-29-2012 at 05:54 AM. Reason: **Only just realised this was a post on the CycleOps board

  9. #9
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    Quote Originally Posted by Jonnyspin View Post
    There must be a relationship to power here?
    Yes. But not one that can be easily modeled. (Spoken with my engineering hat on...)

  10. Default

    FYI, DC Rainmaker just posted a very detailed review (as always) on the PowerCal.
    Inner Drive Cycling|Fitness Studio
    Indoor Cycling|Functional Fitness|Multisport Coaching & Club
    www.innerdrivestudio.com

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