Power Meters - Feel

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Comments

  • GiantMike
    GiantMike Posts: 3,139
    I was wondering whether you had a comparison of your pedalling style with flat and clip-in pedals. Conventional theory suggests clip-ins allow you to transfer more power as you can use more of the top and bottom parts of the stroke than with flats and obviously get some benefit on the up-stroke.

    It sounds like you don't have the comparison, which is a shame.
  • Trev The Rev
    Trev The Rev Posts: 1,040
    GiantMike wrote:
    I was wondering whether you had a comparison of your pedalling style with flat and clip-in pedals. Conventional theory suggests clip-ins allow you to transfer more power as you can use more of the top and bottom parts of the stroke than with flats and obviously get some benefit on the up-stroke.

    It sounds like you don't have the comparison, which is a shame.

    I can only go on memory. Over 4 minutes or 20 minutes or even 60 seconds I was able to generate the same figures using flat or clipless. But at the time that was not my main concern, I was more interested in testing myself and at the same time testing power pedals.

    I really wish Alex would tell us what he thinks.
  • trickydisco
    trickydisco Posts: 173
    GiantMike wrote:
    benefit on the up-stroke..

    IF you mean pulling of the up stroke then it's a myth

    http://roadcyclinguk.com/riding/bike-fi ... troke.html
    Dr Jeff Broker has done extensive pedalling kinesiology tests on 100 elite and professional cyclists over 10 years and his data shows that not one of them produces a meaningful upstroke.
  • Herbsman
    Herbsman Posts: 2,029
    edited November 2012
    Trev The Rev wrote:
    Herbsman wrote:
    Trev The Rev wrote:

    Wattbike measures power at the crank so if one pedal type was more efficient at transferring power the meter should be able to pick it up.
    Wrong.

    Yes I was wrong. It measures from a load cell on the chain. My point being it measures the power after the pedals not at the pedals.
    Exactly. Which is why it can't pick up loss of power via the pedals.

    A crank based power meter only measures the amount by which the electrical resistance through the strain gauges changes as the crank spider flexes. It does not measure energy losses, thus it cannot show how efficient the pedals are at transferring power.

    Same goes for chain-based, hub-based or pedal based power meters. The only way to measure energy loss via pedals would be to measure power in vs. power out with different pedals.
    CAPTAIN BUCKFAST'S CYCLING TIPS - GUARANTEED TO WORK! 1 OUT OF 10 RACING CYCLISTS AGREE!
  • Alex_Simmons/RST
    Alex_Simmons/RST Posts: 4,161
    Trev The Rev wrote:
    I'm sure Alex would have an opinion here and would be able to explain more.
    Left-right asymmetry in power output is normal. Per se, it's not a performance concern.

    The level of asymmetry varies individual to individual, and for any individual it varies depending on a range of factors, such as absolute and relative power outputs, cadence, fatigue, bike fit and so on.

    I could show some data to explain the above, but that would be accolytic :wink:
    RST Sport : Coaching - Training Plans - Powermeters -- My blog -- AeroCoach Australia
  • Trev The Rev
    Trev The Rev Posts: 1,040
    Herbsman wrote:
    Trev The Rev wrote:
    Herbsman wrote:
    Trev The Rev wrote:

    Wattbike measures power at the crank so if one pedal type was more efficient at transferring power the meter should be able to pick it up.
    Wrong.

    Yes I was wrong. It measures from a load cell on the chain. My point being it measures the power after the pedals not at the pedals.
    Exactly. Which is why it can't pick up loss of power via the pedals.

    A crank based power meter only measures the amount by which the electrical resistance through the strain gauges changes as the crank spider flexes. It does not measure energy losses, thus it cannot show how efficient the pedals are at transferring power.

    Same goes for chain-based, hub-based or pedal based power meters. The only way to measure energy loss via pedals would be to measure power in vs. power out with different pedals.

    Obviously, I was only able to use maximal efforts, perceived exertion and heart rate and compare that to the power as measured by the power meters, the speed & distance travelled. I was unable to find a difference between pedal types. This may be down to the fact I can not measure power in accurately enough, although I have been able to see a difference between rear wheels, a Mavic Open Pro 32 spoke wheel and a 32 spoke 30mm deep rim.

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