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  1. #1
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    Reputation: Enel's Avatar
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    Comandante chainstay length spec error?

    Ventana's stated chainstay length for El Comandante is 17.9"

    I have never been sure about exactly where in the throw of the EBB that measurement was taken because even with my EBB in the furthest back (shortest) position, I was measuring 18-18.1". It is unusual for a Ventana to be out of spec in the least, so this confused me.

    I think I finally have it figured out: The spec is wrong. Or I should say the spec was determined by the non-EBB Padrino and just carried over the El Comandante? I am assuming here that the chainstays from the edge of the BB shell back are identical between the SS and geared bikes. This portion of the chainstays measures 17" on my Comandante. The Padrino BB shell measures 1.8" in diameter, and 1/2 of that is 0.9", so total of 17.9" chainstay length.

    When the EBB bike is fitted with its larger shell, the chainstay length effectively increases because the chainstays and the machined piece connecting the stays to the BB shell are not changed to account for the larger shell. The shell is 2.5", so the chainstays on the EBB bike are 17" + (1/2x2.5)= 18.25" This is measuring from drop-out to center of EBB shell.

    It is very long no matter how you measure it.

    The question I have is why?

    Is it a manufacturing issue? Something to do with the machined bridge between the BB shell and tubing on the stays?

    Ventana does not strike me as a company that takes shortcuts rather than producing the best bike they can in every way.

    Seems to me that on a dedicated SS bike with no front derailleur to worry about you should have shorter chainstays unless there is some compelling reason to do otherwise. I think the shorter chainstays would be of benefit to the mostly standing while climbing SS rider who does not need to worry about the front end lifting in steep seated climbs.

    I am no bike designer, generally love my Comandante, and would be interested in knowing the thought process behind this.

    Aaron?

    Hopefully, they will correct the spec.
    Quote Originally Posted by buddhak
    And I thought I had a bike obsession. You are at once tragic and awesome.

  2. #2
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    Reputation: Ciclistagonzo's Avatar
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    Can't help ya here. Don't own, don't ride 29'ers although my Toro has the same setup, but I've never bothered to read the spec sheet nor measure the actual stays, I just hop on it and ride.

    -A
    -Aaron G.

    "Before D.W., "anti-squat" was referred to as pedal feedback."

  3. #3
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    Maybe cs length on EBB bikes is measured with the EBB in the most rearward position.
    Quote Originally Posted by buddhak
    And I thought I had a bike obsession. You are at once tragic and awesome.

  4. #4
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    Reputation: Ciclistagonzo's Avatar
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    Maybe, my guess? The website stuff got copied in error.
    I know the Bridge is necessary, even my sons bike uses it.

    BTW U2 3D rocks.

    -A
    -Aaron G.

    "Before D.W., "anti-squat" was referred to as pedal feedback."

  5. #5
    Neg reppers r my biatches
    Reputation: FoShizzle's Avatar
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    maybe it doesnt matter nor do any individual measurements frankly (within reason). the whole of the bike is what matters, which is not really measurable anyway

  6. #6
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    Quote Originally Posted by FoShizzle
    maybe it doesnt matter nor do any individual measurements frankly (within reason). the whole of the bike is what matters, which is not really measurable anyway
    No doubt, but it doesn't keep me from overanalyzing things.

    Troy Mcclure voice: "I'm not a bike builder, but I play one on MTBR"
    Quote Originally Posted by buddhak
    And I thought I had a bike obsession. You are at once tragic and awesome.

  7. #7
    Neg reppers r my biatches
    Reputation: FoShizzle's Avatar
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    Quote Originally Posted by Enel
    No doubt, but it doesn't keep me from overanalyzing things.

    Troy Mcclure voice: "I'm not a bike builder, but I play one on MTBR"
    lol

    yes, we r all guilty of analysis paralysis at some point

  8. #8
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    Reputation: OldHouseMan's Avatar
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    I think you're being to Enel, I mean anal.

  9. #9
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    Finish

    To bring closure to this pathetic thread:

    I discussed it with Sherwood. The specs are measured with the EBB placed in a position identical to the Padrino. This position is when the eccentric is in the down and back position when the center of the EBB lines up with the center of the seat tube.

    The yolk is unique to either El Comandante, and is a little shorter than the Padrino one.

    In short, the Padrino and Comandanted are designed to have identical measurements when the eccentric is in line with the seat-tube in the lower position. This involves a shorter yolk, and moving the eccentric shell forward relative to the seat tube.

    Also, I can't measure with better than 0.2" accuracy using a tape measure in the garage.
    Quote Originally Posted by buddhak
    And I thought I had a bike obsession. You are at once tragic and awesome.

  10. #10
    Neg reppers r my biatches
    Reputation: FoShizzle's Avatar
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    i hope you can sleep now

    Vassago Cycles Hater Disclaimer says it best, for all us armchair engineers, that "Any one frame dimension doesn't denote a specific handlilng characterstic". As such, a bike with a short chainstay, made out of spam, will not have the riding characteristics that people like to believe is entirely due to short chainstays...my 2 cents anyway

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