"The universe is expanding." Alvy Singer
one guy can't tell us if he's designing, building, or measuring a bicycle, and another guy no longer does any of it. i'm now in the red zone. not the red and white zone; the red zone. what exactly do you want me to say, measure, or concede to??! e-RICHIE chester, ct
On Wed, 11 Aug 2004 14:02:04 -0700 (PDT) Joe Starck
<josephbstarck@yahoo.com> writes:
> -- Richard M Sachs <richardsachs@juno.com> wrote:
>
> "my way of measuring (measuring along the centerline
> of the frame's central plane) yields the half cm diff
> that you note, not the 1 ephgrave mm that you not
> after the fact. "
>
> Richard,
>
> Let's consider a 42 cm chainstay length and 8 cm drop.
>
> Side view of the frame:
>
> The designated chainstay length is 42 cm measured from
> center of bottom bracket to center of rear axle,
> PARALLEL TO THE GROUND, and the rear axle position is
> achieved by default on a vertical dropout, whereas
> with the use of a horizontal, it's anywhere the
> builder prescribes, in my case, it was always to the
> midway position that the axle could be positioned in
> the dropout, using primarily 1010B or shorter
> horizontals (Is this within Don's 6-9 mm axle/hanger
> edict?)
>
> Now then, this above set-up on a frame jig means that
> the measurement along the somewhat centerline of the
> chainstay, I say "somewhat because the dropout center
> is 'neath it, measured from center of BB to center of
> axle position, should be set at a bit less than 42.7
> mm, being the hypotenuse of the 42 cm leg of the
> triangle.
>
> So, say 6 mm difference there.
>
> Now then,
>
> Top view of the frame:
>
> Same 42 mm length, and yet the hypotenuse leg is a wee
> bit shorter, by about one millimeter. And when
> measured from outside of crank bolt to outside of
> skewer the differnce is less, as the measurement is
> now close to being parallel to the plane of the main
> triangle. But who cares about the top view, right? It
> was this dimension I was thinking about when I stated
> the one ducky difference, and so I yes, I contradicted
> myself , but in err' only. My bad.
>
> Still, I would think that if a Sachs owner (Is Richard
> Cielec a Sachs owner?) were to measure his chainstay
> length from outside of crank bolt to outside of
> skewer, center to center, and came up with 42.5 on an
> 8 cm or so BB-drop-designed frame of yours, subtracted
> 5mm netting 42 cm, he has indeed measured his
> chainstay length quite nicely and precisely.
>
> Starck,
> Joe
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