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I would like to discuss Colnago geometry because I want to understand some of their characteristics. I presently have a Masterlight in a 55c-t which fits very well. I'm getting built a fully luged Columbus Max frame based on my present geometry. With other frames i fit a 52cm c-c which fits fairly well but the head tube always seems to be a bit short.

Since on paper a 52cm c-c with a 53.5 top tube with a 119mm head tube witha 72 head angle stretches me more than my 53cm c-c 54.3 toptube with a126 mm head tube and a milder 71.7 head angle. Is this a combined factor of the head angle and the head tube?

My second question is, my masterlight has slightly different measurements than other Traditional Colnago models. Namely the head tubes on other traditional sizes in my size is a 141mm head tube. So my question about this is that does this shorten the top tube even more than my master?

The over all factor to my really liking Colnago geometry is the fact of the milder head angle and the longer front to center, this seems to make the bike track better and slow the steering down.

I'am trying to dial the new build and really want to get it right

thanks
 

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seat tube angle...

Since on paper a 52cm c-c with a 53.5 top tube with a 119mm head tube witha 72 head angle stretches me more than my 53cm c-c 54.3 toptube with a126 mm head tube and a milder 71.7 head angle. Is this a combined factor of the head angle and the head tube?
This statement makes no sense, because it makes no mention of the seat tube angle.
The head tube angle has very little effect on the reach.

The seat tube angle affects the frame reach. With the saddle in a given position relative to the BB, steeper STAs increase the reach. Without the STA of of both frames, either one could have alonger reach, but if they are the same angle, then the 53cm frame has a longer reach.

To get bike to fit a certain way, you need to have the desired head tube length, with the headset, the desired STA and TT length combination to produce a specific reach and the HTA/fork offset combination to produce the desired steering trail. If you don't understand these relationships, you'll be disappointed if you specify the geometry to a builder and then don't like the results.

The only change that's been made to Colnago geometry in a long time is an across the board increase of 7mm in the HTL several years ago.

To answer your question about TT length, it's measured along the centerline of the TT, to the intersection points with the HT and ST centerlines. The head tube can be made longer without changing the c-c frame size, if desired, although it would look strange on a lugged frame.
 
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