Accuracy of computrainer when climbing ?

Discussion in 'Power Training' started by bradgregory, Sep 9, 2003.

  1. bradgregory

    bradgregory New Member

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    I'm interested if others have found that the accuracy of the computrainer when climbing hills doesn't seem good.
    I've found that the speed and power readings seem much to high based on comparing Andrew Coggin's published power profiling data and my own performance level in real races...

    http://www.cyclingpeaks.com/powerprofiling.xls

    E.g. The computrainer indicates I'm riding at 350W on a 7% gradient, which I can maintain for 20 minutes. Given that I weigh 64Kg, this converts to a power/weight ratio index of 350/64 = 5.47. Based on the power profiling data this would place me into the UCI Div I/II Pro category.
    Another example is that my 5 minute hill climb power is shown as 400W by the computrainer, which equates to an index of 6.25, which again is at the same UCI Div I/II Pro level!

    Now I know I'm a half decent hill climber, but I'm pretty sure that based on my performances in TTs, that I'm not a UCI Div I/II Pro!

    The other factor is that if I try to ride at 350W on the flat, this seems like a much harder effort than the same power when climbing, which I can only maintain for maybe 8-10 minutes at the max. I'm not sure if this is perception of effort or a real physiological effect ?

    I use a total weight of 64(rider)+12(bike) = 76Kgs for the weight factor on the computrainer.

    Has anyone found similar inaccuracies or am I a UCI Div I/II Pro :)
     
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  2. ART

    ART New Member

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    I have had very accurate results with the Computrainer both with climbing and on the flats. Given my weight plus bike weight my times correspond on the flats almost exactly with Joe Friels chart showing TT wattage needed for a 40k referenced with respect to rider/bike weight and time to completion. My wattage on hills and my average wattage over many many rides on the Computrainer when referenced to Coggin's chart and then compared to my riding ability on the road relative to cat 2, 3 and 4 riders appears to be right on the money. Computrainers are known to need recalibration now and again which may be your problem. Also do you go through the calibration process as outlined in the owners manual every time you ride since this process is crucial to the accuracy of wattage readings. In addition, on the road when I climb I put out a disproportionally higher wattage over time than I do on the flats--all of which I believe is a function of lower gearing and cadence differences when climbing just playing better to my physiology.

     
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