For those who read what I write from time
should not be news that several times I have highlighted a very important feature
about the design of carbon bicycles today, namely that all programs of
simulations and prototype testing are used for size average. This aspect, which
I have often pointed out to me it was confirmed to the various presentations of
new models from various design engineers.
In practice what this means? It means that
all the effort of "research and development" is focused on only one
combination fork-frame, namely that the average size of the range, while for
the other sizes, in particular to the "end" of the range (the
smallest and the larger) you go "to experience" as an engineer told
me once. Or adding or removing layers of carbon fiber in some areas of the
frame depending on the size.
What I am is what I learned, and I've often
tried to bring out even in our tests, is that the characteristics of the frames
along the range of the same model are not perfectly linear, ie the number of
frames of different sizes are not simply " scale "with respect to one
another, but they may have different characteristics from the dynamic point of
view. What that over the years I have been able to verify in some way since the
feedback we gathered on bicycles of different sizes were sometimes very
different depending on the size used. In particular regarding different sizes of
the model at that time I was using.
This led me to think that often poles apart
sizes in the range of the same model are simply "different bike" and
not just the same bike in different sizes.
When Chris D'Aluisio , chief designer of
the new
Specialized Tarmac , began to introduce the new bike as exposing the great
novelty of this model was that each size (in the range of 7 total) has been
designed and independently thanks to the dynamic testing facts of each size ...
we say that has broken through the traditional open door ...
And in fact, the new Specialized
Tarmac door so, finally, the news that I personally have been waiting for
to / from the design world of bicycles today.
But from the beginning, or from the name,
which is not, as many expect SL5 , but simply Tarmac , leaving aside the
consecutive numbering, which in effect was now reserved only to the Tarmac.
Other new features are a shorter seat tube
of 2 cm which houses the new
integrated system of closure of the seat post (longer than the SL4).
As mentioned, however the most important
features to be found in the differences in size for size. For each size has
been developed a layup just carbon, ditto for the design of the headset
bearings. In particular, in the development phase the prototypes for each size
were equipped with accelerometers and strain gauges to evaluate the lateral
bending and torsion of the frame with equal acceleration curve. This allowed us
to precisely calibrate the construction of the frame in the same type of lay-up
and the amount of carbon for each size, so as to offer the same feeling of
driving from 49 to 61 (or 64 for international).
In a nutshell this what he meant? Here,
too, I have to say (with a little 'satisfaction) that Specialized has
broken through an open door: they have "softened" the frames in sizes
small and stiff ones in large size. What that also in the nose, especially for
those who, like this writer, is accustomed to use large sizes, it was not hard
to predict, because in a few decades of cycling, from memory, have always been
more cases of bike in big size with push-ups and dangerous shimmy , which is
not the testimony about those small in size.
And the results were very interesting,
since the difference in terms of lateral bending given by weight rather than
the height of the center of gravity of the rider above the bike. Well, perhaps
so counterintuitive, the result is that most influences (more than double) the
height of the center of gravity which is not a difference in weight. That is,
about the same size has more influence svettamento one more seat than
non-cyclists of the same height, but different weight.
We mention, even without having seen it
live, the introduction of the brake disc, which also presents an interesting
novelty to him lviello design. The new Tarmac disc adopts in fact the spacing
of the rear 135mm , as for
the bike. Size, however, that brings the problem of the line when this chain is
on the smallest sprocket, making her to be more "external". This,
combined with a short wagon brings the chain to crawl on the front derailleur
cage with certain intersections. And this is the basis of the wagons on average
longer that you can find on bikes equipped with disc brake (not by chance
someone will have noticed that so far have been introduced especially on models
"endurance" of the various producers, who already have floats longer
). A wagon longer, however, obviously has an overall impact on the entire
geometry of the bike and the handling of the same, especially on models more
"racing". Specialized has solved the problem thanks to a hub that
brings the sprocket more inside, coupled to the recessed rear derailleur
inwards. Thus restoring the chain line in the usual position.
During the presentation was also attended
by Michael Rogers (Saxo-Tinkoff) who spoke about his experience with the new
tarmac, a frame that has already started to develop during the last winter
(Rogers is considered a very valuable by Specialized tester because of its
openness mental). Inevitably spoke very well, for example the saying of Venge
also prefer it in stages fast (he also confessed to using the aerodynamic
helmet in these steps only if it rains or is cold and that the whole team is
now using the tubes from 24mm
to 7 bar is front and rear thanks to the instructions of the various tests
instrumental). He spoke then more widely in the department of Specialized
Racing. Department created by the American company to try to maximize the
famous "marginal gains" on the heels of other top teams, with great
use of technological discoveries . Marginal gains that course for many cyclists
are often branded as "usual crap," but instead are doing slowly go
out cycling or roughly the era of hyperbole bar.
After so long, but due, introduction and
presentation has not been that prove the bike. Test carried out on the hills
between Modena 24mm tires which gave me the impression of having an
excellent grip.
Of course, to better understand the pros
and cons of a bike should be, as always, try it for longer, on different paths
and perhaps with different wheels. What we do willingly if there will be the
opportunity to do so.
