Training with Power

Discussion in 'Road Cycling' started by Mdl, Sep 21, 2003.

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  1. Mdl

    Mdl Guest

    Hi, Anyone have any experience using the "Tacx Grand Excel"? I'm looking to buy a trainer that will
    measure power to use over the winter. Any feedback aprpeciated. Thanks.
     
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  2. Robert Chung

    Robert Chung Guest

    MDL wrote:

    > Anyone have any experience using the "Tacx Grand Excel"? I'm looking to buy a trainer that will
    > measure power to use over the winter. Any feedback aprpeciated.

    I don't have any experience with the Grand Excel but since you say that any feedback is appreciated
    I'll mention that the cost of a built-up Power Tap wheel plus a regular trainer is in the same
    ballpark. Each approach has advantages and disadvantages. The main advantage of the PT/trainer
    approach is that you can take it on the road when the weather turns nicer.
     
  3. Dan Gregory

    Dan Gregory Guest

    "MDL" <[email protected]> wrote in message news:[email protected]...
    > Hi, Anyone have any experience using the "Tacx Grand Excel"?
    I used one all last winter and it provides more variety than a simple turbo, Good for ramp tests
    etc. But still a very uninspiring way to ride my bike. All the best Dan Gregory
     
  4. Phil Holman

    Phil Holman Guest

    "MDL" <[email protected]> wrote in message news:[email protected]...
    > Hi, Anyone have any experience using the "Tacx Grand Excel"? I'm looking
    to buy
    > a trainer that will measure power to use over the winter. Any
    feedback
    > aprpeciated. Thanks.
    >
    Accuracy was a concern and has been discussed here before. In a test comparing the Tacx at level 3
    with a Power Tap, I recorded the following (in watts):

    >PT Level 3 Tacx 150 150 175 170 200 190 225 210 250 230 275 250 300 270 325 290 350 310 375
    >330 400 350

    The tacx correlated differently at different level settings which tended to indicate that it was the
    source of the error. I always found that comparative estimating was just as useful (or useless) as
    absolute power values. In my opinion the tacx will still be a useful training tool.

    Phil Holman
     
  5. Robert Chung

    Robert Chung Guest

    Phil Holman wrote:

    > Accuracy was a concern and has been discussed here before. In a test comparing the Tacx at level 3
    > with a Power Tap, I recorded the following (in watts):
    >
    >> PT Level 3 Tacx 150 150 175 170 200 190 225 210 250 230 275 250 300 270 325 290 350 310 375 330
    >> 400 350
    >
    > The tacx correlated differently at different level settings which tended to indicate that it was
    > the source of the error. I always found that comparative estimating was just as useful (or
    > useless) as absolute power values. In my opinion the tacx will still be a useful training tool.

    Phil, I remember when you posted these data:

    http://www.google.com/groups?selm=a%25Xy9.1685%24tW4.198881%40newsread1.prod.itd.earthlink.net

    I went back through that thread, but I didn't see whether you guys had done a rolldown calibration
    for the Tacx before this. Had you?
     
  6. Robert Chung

    Robert Chung Guest

  7. Mdl

    Mdl Guest

  8. Phil Holman

    Phil Holman Guest

    "Robert Chung" <[email protected]> wrote in message news:[email protected]...
    > Phil Holman wrote:
    >
    > > Accuracy was a concern and has been discussed here before. In a test comparing the Tacx at level
    > > 3 with a Power Tap, I recorded the
    following
    > > (in watts):
    > >
    > >> PT Level 3 Tacx 150 150 175 170 200 190 225 210 250 230 275 250 300 270 325 290 350 310 375 330
    > >> 400 350
    > >
    > > The tacx correlated differently at different level settings which
    tended
    > > to indicate that it was the source of the error. I always found that comparative estimating was
    > > just as useful (or useless) as absolute power values. In my opinion the tacx will still
    be
    > > a useful training tool.
    >
    > Phil, I remember when you posted these data:
    >
    >
    http://www.google.com/groups?selm=a%25Xy9.1685%24tW4.198881%40newsread1.prod.itd.earthlink.net
    >
    > I went back through that thread, but I didn't see whether you guys had done a rolldown calibration
    > for the Tacx before this. Had you?

    I've only ever seen a calibration rolldown on a Velodyne. The Tacx unit belonged to someone I was
    coaching and it had no calibration feature on it and no mention of it in the literature. Researching
    the Grand Excel model, it is the same as the Excel plus a bunch of programming capability. What was
    the reason for your question? Without taking into account tire rolling resistance, the difference
    between a 25mm tire at 90psi and a 21mm at 130psi will result in a significant difference in actual
    power generated with the Tacx unit.

    Phil Holman
     
  9. Andy Coggan

    Andy Coggan Guest

    "Phil Holman" <[email protected]> wrote in message
    news:[email protected]...
    >
    > "Robert Chung" <[email protected]> wrote in message
    > news:[email protected]...
    > > Phil Holman wrote:
    > >
    > > > Accuracy was a concern and has been discussed here before. In a test comparing the Tacx at
    > > > level 3 with a Power Tap, I recorded the
    > following
    > > > (in watts):
    > > >
    > > >> PT Level 3 Tacx 150 150 175 170 200 190 225 210 250 230 275 250 300 270 325 290 350 310 375
    > > >> 330 400 350
    > > >
    > > > The tacx correlated differently at different level settings which
    > tended
    > > > to indicate that it was the source of the error. I always found that comparative estimating
    > > > was just as useful (or useless) as absolute power values. In my opinion the tacx will still
    > be
    > > > a useful training tool.
    > >
    > > Phil, I remember when you posted these data:
    > >
    > >
    >
    http://www.google.com/groups?selm=a%25Xy9.1685%24tW4.198881%40newsread1.prod.itd.earthlink.net
    > >
    > > I went back through that thread, but I didn't see whether you guys had done a rolldown
    > > calibration for the Tacx before this. Had you?
    >
    > I've only ever seen a calibration rolldown on a Velodyne. The Tacx unit belonged to someone I was
    > coaching and it had no calibration feature on it and no mention of it in the literature.
    > Researching the Grand Excel model, it is the same as the Excel plus a bunch of programming
    > capability. What was the reason for your question? Without taking into account tire rolling
    > resistance, the difference between a 25mm tire at 90psi and a 21mm at 130psi will result in a
    > significant difference in actual power generated with the Tacx unit.

    Robert asked because a standard procedure for coast-down calibration of the Tacx has been proposed
    and adopted by at least some. If followed, the Tacx tends to give more accurate power data than what
    you're reporting.

    Andy Coggan
     
  10. Phil

    Phil Guest

  11. Phil Holman

    Phil Holman Guest

    "Andy Coggan" <[email protected]> wrote in message
    news:[email protected]...
    > "Phil Holman" <[email protected]> wrote in message
    > news:[email protected]...
    > >
    > > "Robert Chung" <[email protected]> wrote in message
    > > news:[email protected]...
    > > > Phil Holman wrote:
    > > >
    > > > > Accuracy was a concern and has been discussed here before. In a
    test
    > > > > comparing the Tacx at level 3 with a Power Tap, I recorded the
    > > following
    > > > > (in watts):
    > > > >
    > > > >> PT Level 3 Tacx 150 150 175 170 200 190 225 210 250 230 275 250 300 270 325 290 350 310 375
    > > > >> 330 400 350
    > > > >
    > > > > The tacx correlated differently at different level settings
    which
    > > tended
    > > > > to indicate that it was the source of the error. I always found that comparative estimating
    > > > > was just as useful
    (or
    > > > > useless) as absolute power values. In my opinion the tacx will
    still
    > > be
    > > > > a useful training tool.
    > > >
    > > > Phil, I remember when you posted these data:
    > > >
    > > >
    > >
    >
    http://www.google.com/groups?selm=a%25Xy9.1685%24tW4.198881%40newsread1.prod.itd.earthlink.net
    > > >
    > > > I went back through that thread, but I didn't see whether you guys
    had
    > > > done a rolldown calibration for the Tacx before this. Had you?
    > >
    > > I've only ever seen a calibration rolldown on a Velodyne. The Tacx unit belonged to someone I
    > > was coaching and it had no calibration feature on it and no mention of it in the literature.
    > > Researching the Grand Excel model, it is the same as the Excel plus
    a
    > > bunch of programming capability. What was the reason for your
    question?
    > > Without taking into account tire rolling resistance, the difference between a 25mm tire at 90psi
    > > and a 21mm at 130psi will result in a significant difference in actual power generated with the
    > > Tacx unit.
    >
    > Robert asked because a standard procedure for coast-down calibration
    of the
    > Tacx has been proposed and adopted by at least some. If followed, the
    Tacx
    > tends to give more accurate power data than what you're reporting.
    >
    > Andy Coggan

    Sounds reasonable. Calibration would therefore be via adjustment of tire inflation/roller pressure?
    Based on my data, I could see that a higher pressure and narrower tire would tend to make the unit
    read more accurately. Someone must have been busy with a calculator.

    Phil Holman
     
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