Powertap SL - resetting torque

Discussion in 'Power Training' started by NomadVW, Jan 7, 2007.

  1. NomadVW

    NomadVW New Member

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    I went for some 3700km before ever having to zero the torque on my SL. On the 2nd after a particularly hard day on the 1st, I was coasting at 35 watts. Today I went out the door and it was off again.

    How often do you all find you are resetting the torque to zero on your powertaps? If this is a normal thing, I'll not worry about it and start doing it before every ride just in case. Not having had to do it in the first 2 1/2 months of ownership makes me worry when I've done it twice in a week now.
     
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  2. Bruce Diesel

    Bruce Diesel New Member

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    Hmmnn.. This started happening to me recently as well.

    One thing I did notice, was that the PowerAgent 7 software has a tick box to "Automatically adjust torque" which was ticked. My weird behaviour seems to correlate with downloading PowerAgent 7 and changing some of the device settings.

    I have sent a note through to the guys here in S.A. asking what this option does, but maybe someone on the forum can illuminate?
     
  3. NomadVW

    NomadVW New Member

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    I've never used the Poweragent software, so I can't relate there. Hopefully others can chime in.
     
  4. Alex Simmons

    Alex Simmons Member

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    Me either.

    It happens to me every now and then.

    I usually put little unusual happenings down as the first sign of batteries on their way out. But I usually re-zero before every ride anyway (even if it says zero) and try to have a 10 second coast within the first 5-10 minutes just to check.
     
  5. NomadVW

    NomadVW New Member

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    Ya know what. I bet I know what it is.

    I'm betting we all use "Pedal" only for the cadence. While using Pedal/Hub until around the 16/17th of December I never had this problem. The Hub setting would allow the computer to guesstimate cadence and know if it was "spinning" or not. Therefore, the "autoset" for Torque would autozero when the hub was estimating 0 cadence (therefore zero power).

    Thoughts?
     
  6. Alex Simmons

    Alex Simmons Member

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    Not AFAIK.

    The hub auto zeroes when no torque is applied and coasting as long as the zero offset is within +/- 8 in lbs. Large changes in temperature can cause the offset to move outside this range. I notice it sometimes if I've had the bike on the roof of the car.

    See post on wattage:
    wattage PT auto zero
     
  7. NomadVW

    NomadVW New Member

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    Maybe it just comes down to me storing the bike inside and taking it outside. That's a .. well.. big temperature change this time of year.
     
  8. Bruce Diesel

    Bruce Diesel New Member

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    I don't have big temperature changes, but I did change my setting to "Pedal Only" cadence after I was getting wierd cadence readings.

    Also had to change the batteries recently, so it could have been any one of these things.
     
  9. Spunout

    Spunout New Member

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    Batteries for me. I need to re-set a few times, then the batteries go. First day on new batteries will require a re-set, then we're good for a few months.
     
  10. decrono

    decrono New Member

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    Alex I smell a mild SRM zeroing creeeping into you.
    Perhaps you have spent way too much time riding with SRM junkies;)

    peter
     
  11. Alex Simmons

    Alex Simmons Member

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    actually it's more to do with regularly riding a fixed gear PT hub - you need to check it regularly on a fixed gear since you have to turn off the auto zero function. As a habit it's not a bad thing....;)
     
  12. Bruce Diesel

    Bruce Diesel New Member

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    Hmmn, I am having all sorts of glitches at the moment wth my Powertap. Replaced the hub batteries and the CPU batteries recently, then today the display was fading out every now and then. Then, suddenly it blinked and all my data was gone :eek:. After that it was fine for the rest of the ride.

    Fortunately I am also riding with an Ergomo testing it out so all is not lost.
     
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