Colnago geometry questions

[Dave B]

I am looking for a Colnago frame/fork.

I ride a 56.6 TT on my road and cross bikes. So I am looking for a 56ish TT in a colnago. I also use a 110mm stem.

When I look up C-50, Extreme-C etc, I see a 57/58 in the traditional comes the closest and a 54s in sloping.

I have been offered frames in the 56cm Traditional and folks are saying that due to the angle of the HT that to get a proper feel I need a 56cm with a 120mm stem for proper balance.

For those of you in the know or understand this better, is this right? or do I need to stick to a 57/58 trad and 54s?

I need to gather information as my lack of knowledge and angles and how it affects the bike is not nearly as strong as some of you.

Cheers

[LegendRider]

I ride a 54s Colnago C50 with a 120 stem. My saddle height is 77cm and my saddle to bars measures 57cm. In a traditional, I'd ride a 58.

With my set-up I think the bike looks balanced - saddle isn't too high or low and bars don't require a bunch of spacers. It definitely handles nicely.

For perspective, I also have a Parlee that has a level top tube and it's 57cm square.

[mgm777]

I too want to read the answer to this question from those in-the-know. I have oftern heard the same about Colangos, that they ride best with a 120 stem. I don't have a Colnago, but am intrigued. I typically ride road bikes with a 55 TT. Wonder what the appropriate Colnago size would be assuming the 120 stem requirement is accurate?

[wooly]

I've had a number of Colnagos and think the advice on running a 120 or even 130 stem is sound due to the slacker head tube angle. I usually ride a 55.5 to 56 top tube and a traditional (in Colnago speak) 56 fits spot on as does a 52 sloping. In addition to the adjustment in size to accommodate a 120 stem be sure that the head tube length is going to work.

[christian]

Not to go all Jerk on you, but all proper racing bikes handle most appropriately with a 120-130mm stem.

[Germany_chris]

yup..had a 130 on mine..

[Mudbug]

Colnago's are notorious for short top tubes. I like 'em but I can ride 'em for that reason.

[Dave]

A TT length without a seat tube angle to go with it is meaningless. Both are needed to determine the reach of the frame. For example, if you have a 56cm TT with a 73 degree STA, and another frame with a 55cm TT and a 74 degree STA, they will fit almost identically, once the saddle is placed in the same position, relative to the BB. To figure the difference more accurately, use the formula (cosA- cosB) times the c-c frame size. Colnago lists both c-c and c-t dimensions on their geometry charts.

The HTA makes very little difference in the fit - on the order of 1-2mm per degree. Colnago HTA's tend to be slack, creating more steering trail and slower steering than many other brands, using the common 43mm fork offset.

The idea that a certain stem length is appropriate for a Colnago is nonsense. You use whatever is needed to get the reach required.

[1centaur]

To keep the anecdotes coming, I would traditionally ride a 57.2 TT with a 120 stem, while I ride a 58 Colnago (56.3 TT) with a 130 stem. I am fine recommending TT + stem length (same stem rise) equaling the same and not imagining that a much shorter TT (a 56 Colnago) with a slight lightly longer stem is magically right in some Colnago way that is a mystery. The shallower HT angle gives it a different ride but does not change distances that much.