How does the geometry of a frame come about? On the basis of what criteria are the tube angles studied?
As far as our bicycles are concerned, we can say that there are no secrets: everything comes from the experience of almost 65 years of business activity in building frames used by professionals and enthusiasts.
Ernesto Colnago, who has always been a great experimenter, during 25 Giro d’Italia and 25 Tour de France competitions in which he took part as a mechanic, acquired a huge amount of information on the posture of cyclists: a wealth of knowledge, made up of practical observations, technical surveys and anthropometric data, which enabled him to develop his own geometries and angles, and to achieve current standards.
Colnago’s geometries, transversal to each model, are rather classic and traditional, meaning by this a triangle of balanced proportions to ensure both utmost performance in terms of aerodynamics and handling, and a comfortable position, such as to be able to stay in the saddle for many hours.
For a more technical analysis, “reach” and “stack” values can be taken as a reference, indicating respectively the horizontal and vertical distance between the centre of the central movement and the centre distance of the top part of the head tube, determining, to put it in a nutshell, the length and height of the bike. On our frames, a slightly higher “stack”, together with a reduced “reach”, determine a position in the saddle at the same time higher and more collected up, with a more relaxed and comfortable seat.
All this involves a not-too-steep inclination of the saddle tube, called the seat tube angle, i.e. between 72.5° and 75.5°, depending on the model and size. The head tube has a length that we can consider average: taking into account the C64 frame, this goes from 115 mm of the size 42s to 219 of the 60s.
The combination of these features permits maintaining an excellent level of comfort even on bicycles designed to achieve high performance.
Then, of course, everything depends on the habits and physical characteristics of each cyclist: some adopt a more aerodynamic position, bending a lot, while others prefer comfort. From this point of view, our geometries represent an ideal solution and allow everyone to find the position that suits best.
The only deviation from these considerations, in order to provide an even more comfortable option, is the introduction by us of the Geometry H (High), available today on the C64 frame: size being equal, by raising the head tube, we can in other words obtain a more “comfortable” basic setting, without the need to insert a large number of spacer rings between headset and stem.
And in all this, it should not be forgotten that in the event of any special need we are always and in any case able to create fully-customized frames.