# seeking measurements on 585 frame



## tom_h (May 6, 2008)

From anyone having these frames:

-- 2007 or 2008 model, 585 Origin or 585 Ultra
-- size L (55 cm)
-- size M (53 cm)

I would sincerely appreciate an actual measurement of the straight-line distance between these two points, accurate to +/- 1/8" (+/- 0.3 cm), if possible :

point 1: center of Bottom Bracket.
point 2: top of Head Tube, at its center . 

Multiple responses appreciated, so I can calculate averages. Locally, there were only 585 "Optimum" frames available for me to measure.

Thank you!


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## C-40 (Feb 4, 2004)

*thoughts...*

What you want is a stack height measurement, comparable to those provided by Cervelo and Trek. The problem is that you need a bare frame, somehow setup so it's perfectly horizontal. Then you have to project a horizontal line from the center of the head tube and intersect a vertical line from the center of the BB. Good luck with that.

Another method that's nearly as good would be to measure an assembled bike, from the side, from the floor to the center of the head tube, then subtract the BB height from the floor.

I did this for my 585 and came up with a 27cm BB height. All sizes have the same 70mm BB drop. I have a 51cm with the 125mm head tube. I came up with a 79.5cm height to top-center of the head tube, for a stack of 52.5cm.

By extrapolation, the large sizes will have a stack that is 95% of the additional head tube length, plus about 3mm for the steeper HTA. The stack of the 53cm should be very close to 54.5cm and the 55cm should be about 55.3cm.

If you compare a Cervelo with a 120mm head tube, it's stack is 52.2cm and a Trek's is 52.5cm. If my LOOK had a 120mm head tube, the stack would be 52.0cm. I've got an older KG461 with a 120mm head tube and that's just what it measures.


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## tom_h (May 6, 2008)

C40,

Thanks for the detailed answer. Yes, I suppose "stack height" was ultimately the "correct" info. I was trying to encapsulate several fit issues into my original requested measurement.

I'm still a bit confused by the definition and measurement of "stack height" you provided.

Is "Stack height" = ?

1) height of center of head tube – height of center of Bottom bracket. 
2) height at top of HT – height of BB. 
3) height at HT where it is intersected by the Top Tube – height of BB. 

The "reach" , or "B - E" dimension in the attached Look frame drawing, was another critical dimension of interest.

Interestingly, it seems as if 585 Optimum or Origin frame versions _but in different sizes_ would be the best match to my existing geometry, which I don't want to deviate from _too_ much. Assuming, I keep saddle-to-BB distance and setback unchanged.

ie, "reach" of "
-- present bike: 38.7 cm.
-- Large (55cm) Optimum: 39.2
-- Medium (53cm) Origin: 39.7 (adapting to 1 cm more reach would be no problem for me).

I suppose the drop between saddle and top of Head Tube is the last bit of puzzle, and follows directly from "stack height". 

FWIW, 
my height = 5'-10.5" (179 cm) and true bike inseam = 34.0" (86.4 cm).
I think I have reasonably "average" body proportions and am moderately flexible (touching ground with closed fist is no problem, and with some effort, open palms on ground, after limbering-up stretches), Age 56, 168-170 lbs (77 kg).


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## mds (Dec 16, 2008)

On my 2009 585 Origin size L I measure 690mm from point 1 to point 2. The 2009 frame is the same as earlier years, so this number should be valid for 2007 and 2008 also.

By the way, it is possible to compute this measurement given the 585 geometry chart on the Look web site with a spreadsheet. Here is what I calculate:

size L: 686mm
size M: 642mm

The difference between this calculation and my actual measurement is probably due to a bit of measurement error on my part as I am only estimating the BB center on my bike's crank.


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## C-40 (Feb 4, 2004)

*info...*

Stack height is the vertical distance from the center of the BB to the intersection point of the top of the head tube and centerline of the head tube, by Cervelo and Trek's defintion. It is not the same as B minus E on the LOOK geometry chart, because the point at the head tube is the interesction of the TT centerline and head tube centerline.

That's why I said that it's more important to just compare the TT lengths and make the proper correction for differences in the STA. Then compare the head tube length with the appropriate headset stack height.

More relevant than your inseam is you actual saddle height from the center of the BB, measured along the centerline of the seat tube and your actual handlebar height from the floor to the top of the bars. From this info, it's not too hard to predict a head tube length and stem angle to get the bars where you need them.


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