Weight Weenies

Hi. I need help here from the group on Colnago Aluminum bikes. I am considering a brand new, 2016 Colnago Cx Zero Alu Ultegra. I have questions with respect to the sizing/frame size to fit me. I'm 5'8.5" tall with a 30" inseam. Colnago's sizes are a bit foreign to me. Do I need their size 52cm or their size 50 cm? On a Specialized Roubaix Comp, I ride a 54 cm. On a Cervelo R3, I ride a 54 cm. I stopped in at a bike store that carried Colnago and while they did not have this exact frame design, the store thought I needed a 50 cm based on lowest leg position. Can I get any input from you Colnago owners? If I'm in between, do I go smaller or larger? Thanks!

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Couple of answers waiting for you here already: viewtopic.php?f=3&t=138945

I have a few, all sloping top tube variants and so the size has an ‘s’ after it (e.g. 50s / 52s)

Essentially you just add 4cms to get a ‘normal’ size. I ride a 54cm frame size so my Colnagos are size 50s. Traditional (straight top tube) frames should be the same as ‘normal’ bikes. Also I’m about your size so I reckon you too are a 50s.

Hope that helps.

I have a cervelo 56 which has the same stack and reach as my Colnago 54s.
I hope this helps

I'd say 50s too, that will give you a 54cm effective top tube.

A 52s would be 55.5cm effective top tube and probably a bit too long for you.