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  1. #1
    Carpe Diem bdcheung's Avatar
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    SRM offset procedure

    Are you supposed to leave the cranks stationary when doing the offset procedure, or continue rotating the cranks backward?
    "When you are chewing the bars at the business end of a 90 mile road race you really dont care what gear you have hanging from your bike so long as it works."
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    Senior Member djbowen1's Avatar
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    roate backwards, freewheeling until the number is stable.

  3. #3
    Race to train jrennie's Avatar
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    If you want to do it while rolling then the cranks need to be still and both feet need to be out. If you are still clipped in or spinning the cranks the offset will rise.

  4. #4
    Carpe Diem bdcheung's Avatar
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    Quote Originally Posted by jrennie View Post
    If you want to do it while rolling then the cranks need to be still and both feet need to be out. If you are still clipped in or spinning the cranks the offset will rise.
    That's what I thought, and that's what I normally do, but was reading conflicting reports (see post above yours).

    So, to be certain, the offset should be done with the cranks stationary and unloaded. Right.
    "When you are chewing the bars at the business end of a 90 mile road race you really dont care what gear you have hanging from your bike so long as it works."
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  5. #5
    Out of Commission OC Roadie's Avatar
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    Quote Originally Posted by bdcheung View Post
    That's what I thought, and that's what I normally do, but was reading conflicting reports (see post above yours).

    So, to be certain, the offset should be done with the cranks stationary and unloaded. Right.
    This is how I've always done it.

  6. #6
    Carpe Diem bdcheung's Avatar
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    k. you never can be too obsessive about these sorts of things. especially when the Quarq zero-offset procedure can be done while backpedaling.
    "When you are chewing the bars at the business end of a 90 mile road race you really dont care what gear you have hanging from your bike so long as it works."
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  7. #7
    slow up hills kudude's Avatar
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    Quote Originally Posted by djbowen1 View Post
    roate backwards, freewheeling until the number is stable.
    yeah, this is wrong. The strain gauge needs to be entirely unloaded. Sucks if you leave in the early morning and come home when it's 20-30 degrees warmer, because you should probably have cleared it a few times. I'm of the sort who doesn't like to get off his bike, but don't really feel like unclipping both feet and fiddling with the powercontrol while coasting along....YMMV
    Quote Originally Posted by mr_tom View Post
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  8. #8
    pan y agua merlinextraligh's Avatar
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    Quote Originally Posted by jrennie View Post
    If you want to do it while rolling then the cranks need to be still and both feet need to be out. If you are still clipped in or spinning the cranks the offset will rise.
    Quote Originally Posted by bdcheung View Post
    k. you never can be too obsessive about these sorts of things. especially when the Quarq zero-offset procedure can be done while backpedaling.

    In zeroing my quarq, I was curious about this. It would seem that spinning the quarq backwards would have the effect jrennie outlines.

    However, the quarq cinco instructions are clear that you spin it backwards 4-5 revolutions to zero it.

    So I guess the quarq is somehow designed to account for this.
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  9. #9
    Senior Member djbowen1's Avatar
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    [QUOTE=kudude;8256857]yeah, this is wrong. The strain gauge needs to be entirely unloaded. Sucks if you leave in the early morning and come home when it's 20-30 degrees warmer, because you should probably have cleared it a few times. I'm of the sort who doesn't like to get off his bike, but don't really feel like unclipping both feet and fiddling with the powercontrol while coasting along....YMMV[/QUOTE

    Ah yes, i read the manual wrong:

    From SRM:
    Turn the PowerMeter on by pedalling backwards a few times, and then leave the pedals in a horizontal
    position and let go of them. You need to make sure that nothing is touching them or you will end up with
    an inaccurate zero offset. With track systems, put forward pressure on the pedals before setting the zero
    offset.

    Wait until the zero offset stabilises, resting on the same number for a few seconds.

    After the zero offset stabilises, press “Set” to store this value for its power calculations.

  10. #10
    slow up hills kudude's Avatar
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    I tried reading the manual before riding. I just gave up on the description of the powercontrol. I figured I had several hours on the bike to mash buttons until I figured it out. This is to say that their writing on occasion could be clearer.
    Quote Originally Posted by mr_tom View Post
    Cycling isn't a sport. It's more like a really, really expensive eating disorder.

  11. #11
    Ninja don't wear flipflop king-tony's Avatar
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    There is a zeroing procedure and then a similar procedure for checking your pick-up on the wired version. If you have the wired version you can check by moving the crank back a few degrees at a time and checking the offset. If you get a zero or really low number your sensor is not picking up for the full 360 degrees and will give you inaccurate (usually low) power numbers.

  12. #12
    Senior Member djbowen1's Avatar
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    The manual is a bit much, i use it more as a reference. I havent used my srm in over 6 months, which model did you get?

  13. #13
    Village Idiot
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    I've tried doing it both ways and I've ended up with a very similar number both times.

    I normally just pedal backwards. I've tried both when using the trainer and the difference was maybe 2-3, which isn't significant.
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