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Thread: What´s the reasoning behind dropped top tubes on a road bike?

  1. #41
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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by Matthew Strongin View Post
    Sure, if that helps you confirm your predetermined conclusion. .
    I had no predetermined anything. On the contrary: i knew what Kellogg wrote but wanted to know if there was more of it. HIs take is mostly empyrical.
    I came here for the socks.

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by David Tollefson View Post
    He's talking about the feel of swinging the bike side-to-side (it essentially rocks side-to-side about a line through the tire contact patches). The lower the bike's CG, the lower the moment of inertia of rocking the bike about that line. Tom was equating the feel of that lower CG on that moment of inertia of the the sloping design with a bike of a "traditional" design that weighed three pounds less.
    Hmm.. yes but where is the center of gravity on a bike? Isn´t it the BB? Or is it somewhere along the line between BB and saddle?
    I came here for the socks.

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by colker View Post
    Hmm.. yes but where is the center of gravity on a bike? Isn´t it the BB? Or is it somewhere along the line between BB and saddle?
    It doesn't fucking matter where it is. If the metal seat tube is lobbed off (shortened), and the top tube is connected lower still, then the weight is lower to the ground than where it would normally be.

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by e-RICHIE View Post
    It doesn't fucking matter where it is. If the metal seat tube is lobbed off (shortened), and the top tube is connected lower still, then the weight is lower to the ground than where it would normally be.
    The weight of top tube and seatstays... everything else is the same. It´s minimal.
    I came here for the socks.

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by colker View Post
    The weight of top tube and seatstays... everything else is the same. It´s minimal.
    Marginal gains.

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by e-RICHIE View Post
    Marginal gains.
    Stiffness.. then it makes sense: smaller triangles. Compensated by seatpost flex (does a 30.6 seatpost even flex?)
    I came here for the socks.

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by colker View Post
    Stiffness.. then it makes sense: smaller triangles. Compensated by seatpost flex (does a 30.6 seatpost even flex?)
    My work here is done according to my opinion.

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by colker View Post
    Yes. There are different ideas of harmony and balance. I still don´t understand the gains from a slopping top tube on a road bike.
    Putting contact points at the right place without having standover clearance issues or upright stems or else?

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by Guillaume View Post
    Putting contact points at the right place without having standover clearance issues or upright stems or else?
    The Freuler geometry drops the top tube but does not slope. Pegoretti went this way. I know the ahead set is where it all began somehow w/ head tubes getting longer relative to stack but it seems it´s also about the rear triangle as Kellog found out that a smaller rear triangle makes the bike faster to react.
    I came here for the socks.

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Function over form.
    I have a proportionally long torso for my height.
    I have proportionally short legs for my height.
    I have proportionally short arms for my height.

    I share my "custom" Seven Axiom SL.
    Many think it looks off and/or weird.
    I think it looks great because it works for me.
    I trusted my builder(s).

     

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by NYCfixie View Post
    Function over form.
    I have a proportionally long torso for my height.
    I have proportionally short legs for my height.
    I have proportionally short arms for my height.

    With that said, I share my "custom" Seven Axiom SL.
    I trusted my builder(s).
    Many think it looks off and/or weird.
    I think it looks great because it works for me.
    Yes but you could have the same fit and same clearance w/ a parallel to ground top tube.
    I came here for the socks.

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by colker View Post
    Yes but you could have the same fit and same clearance w/ a parallel to ground top tube.
    Incorrect.
    See above comment about short legs, short arms, and long torso.

    I have owned many parallel top tube bikes over the years and know fit was always compromised due to standover height.
    This "custom" frame was built without compromise regrading standover height.

    It was not built because I wanted a sloping top tube, it was built because I needed a sloping top tube.
     

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by NYCfixie View Post
    Incorrect.

    See above comment about short legs, short arms, and long torso.
    Where do you measure stand over? Draw a line parallel to ground on that point. Make it your top tube. Attach to the same headtube. Raise the seat tube if necessary. Or give you even more stand over and keep your seat tube. Look at small Pegorettis and how they do it. You may not fit a frame pump the way you did.. everything else is equal.
    I came here for the socks.

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by colker View Post
    Where do you measure stand over? Draw a line parallel to ground on that point. Make it your top tube. Attach to the same headtube. Raise the seat tube if necessary. Or give you even more stand over and keep your seat tube. Look at small Pegorettis and how they do it.
    I get the sense based on your responses to me and others you are looking for an argument rather than an informed discussion.

    If they used a parallel top tube with the same size headtube, the headtube would not be properly supported. If they went with a parallel top tube and shorter headtube then the fork steerer would not be supported. These would have led to compromises.

    The sloped top tube may make the rear end stiffer but that was alleviated by thinner wall seat stays thus no compromises.

    Your conclusions have no merit.
     

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by NYCfixie View Post
    I get the sense based on your responses to me and others you are looking for an argument rather than an informed discussion.

    If they used a parallel top tube with the same size headtube, the headtube would not be properly supported. If they went with a parallel top tube and shorter headtube then the fork steerer would not be supported, All of these would have led to compromises.

    The sloped top tube may make the rear end stiffer but that was alleviated by thinner wall seat stays thus no compromises.

    Your conclusions have no merit.
    Jesus ... please... no internet drama. I am having an honest down to earth conversation about a very precise subject : geometry.
    I came here for the socks.

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by NYCfixie View Post

    Your conclusions have no merit.
    I just showed you there is another way around your fit numbers w/ a parallel horizontal top tube. What´s the problem?
    I came here for the socks.

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by colker View Post
    I just showed you there is another way around your fit numbers w/ a parallel horizontal top tube. What´s the problem?
    When e-Richie, Tyler/FF, or any of the other respected builders tell me there is a better way, I will believe one of them.
     

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by colker View Post
    I find it ugly and a downgrade. It goes beyond aesthethics: a perfect geometric shape has effects on your psyche. No wonder certain structures and shapes were used in religious temples. Anyway.. i understand a dropped top tube on a mountain bike where standover is paramount. I understand curved top tubes on a cruiser which is about fun and taking it easy. A racing bike otoh is about grace and speed. A horizontal tube, parallel to horizon means balance and balance is necessary for grace in the face of risk. I could go on and on w/ this babbling.
    I know some serious designers like Kellog build w/ dropping top tubes so what´s the deal?
    Quote Originally Posted by colker View Post
    I had no predetermined anything. On the contrary: i knew what Kellogg wrote but wanted to know if there was more of it. HIs take is mostly empyrical.
    Richard dropped an F bomb. This is good stuff. Really good stuff.

    (drew eats popcorn in the corner, patiently waiting).
     

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by e-RICHIE View Post
    It doesn't fucking matter where it is. If the metal seat tube is lobbed off (shortened), and the top tube is connected lower still, then the weight is lower to the ground than where it would normally be.
    Amen.

    CG height no matter on 2 wheel vehicle that leans as it steers.
     

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by NYCfixie View Post
    When e-Richie, Tyler/FF, or any of the other respected builders tell me there is a better way, I will believe one of them.
    Excellent. No need for internet conflict, right? It´s just talking.
    I came here for the socks.

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