Bicycle geometry is driving me NUTS!!!

[synchronicity]

But that's not a very accurate way of doing it.
For one thing it looks like your green tape mark on the head tube is off.

[Karvalo]

anyway, i found the reach on the protos. 385mm

floor is horizontal. bar is horizontal. plumb line bisects BB

gotta do the Look now... measuring from the top of the TT at the center of the HT, like i did on the Protos, reach is also 385

Oh my. You know you could have measured the reach using just the tape measure and a wall, right? You didn't need any of the tape, plumb line, metal bar etc.

this is getting more confusing with each measurement. by all measurements, these 2 bikes are almost identical

edit: persistence beats resistance, but boy do i feel stupid. at least i now know all the measurements!

My point would be, how do you know the saddle setback is different? Did you somehow calculate it from other measurements? If so, is it not more likely that you just got the maths wrong again?

[Visqu]

I find it interesting that in the geo charts for the Protos, the supposed ST angle is drawn to be between the ST and the slightly sloping TT..
Is this really what they are measuring or are they misrepresenting the quantity due to some earlier models having a horizontal TT?

But then looking at other De Rosa geo charts as well, it's suddenly obvious that they have no clue what they are measuring.
For example, the Merak shows the ST angle as that between a vertical line and the chainstay, on the SK Pininfarina this angle then is between a horizontal and a vertical line

Edit. wrote seatstay when I meant chainstay, corrected this.

[1415chris]

Maybe their perspective is that for the fitting purposes ST angle is not important (?)

[Visqu]

Most likely reason is that the guys doing the docs are not really talking to those supplying the data and then no-one is really paying attention to the output.
Your regular corporate process

[bikeboy1tr]

Maybe I missed it but are the saddles the same from one bike to the other. I know when measuring from the nose of a saddle to the bars or how far the saddle is behind the BB it should be somewhat obvious that where you sit on the saddle varies from saddle to saddle. I know my SMP has me positioned further rearward than the Fizik Arionne as I run out of rails with the Fizik wheras the SMP still has rail left when I am sitting in the same position. Just a thought.

[efixler]

i ve a look 585 and a 595...

Which one do you like better?

[jasjas]

i ve a look 585 and a 595...

Which one do you like better?

I like both, i'd never sell either, stiff but comfy but the 595 has the better grpset and wheels, so its the bike i take abroad.

I think the 595frame is very under rated, i ve a new ish TCR Adv and the 595 is "better" and lighter, 6.9kg with DA, inc pedals, carbon tubs @1250g.

[MrCurrieinahurry]

I had both a 595 and 585 miss my 585 more due to it being more comfy

[efixler]

Thanks [mention]jasjas [/mention] and [mention]MrCurrieinahurry [/mention] - both bikes I’d like to try someday!

[tcxuzuo]

i ve a look 585 and a 595...

Which one do you like better?

I like both, i'd never sell either, stiff but comfy but the 595 has the better grpset and wheels, so its the bike i take abroad.

I think the 595frame is very under rated, i ve a new ish TCR Adv and the 595 is "better" and lighter, 6.9kg with DA, inc pedals, carbon tubs @1250g.

Is there any difference between adv and adv pro,mainly the weight of fork and frameset

[otoman]

The bottom bracket is not in line with the seat tube on the DeRosa. The center of the BB is rearward from the line created by the seat tube. Cervelo started this nasty little trick years ago. So they came up with stack and reach to take the ST out of the fitting equation.

Just make your stack and reach the same on both bikes using the technique described above with a tape measure and a wall.

[104Sancta]

Are you not perhaps stressing about unimportant issues. Have you ridden both bikes? If so how do they ride? Which bike would you prefer to own? That is the one you should buy. After a few rides you won't notice those differences of a few millemeters.
Stop worrying about it and just enjoy your riding.

[morganb]

I've seen this in other bikes, I had a 54 Allez Sprint and 52 SL6 Tarmac at the same time, same saddle both 74deg SA. To get my setback relative to the BB in the same place, the Sprint had a 0 offset post with the saddle pushed slightly fore of center, while the Tarmac had a 20mm setback post, with the saddle slightly aft of center. With non-straight seat tubes, much like all of the wacky full suspension MTB geometry, there is effectively a virtual and actual seat tube angle, with one variable based on saddle height.