Originally Posted by
DaveSSS
One of the problems with this comparison is it's apples and oranges. The C'dale is a relaxed fit bike with a 20mm taller head tube and the BMC is a bike with a racing fit and normal head tube length, for a given size.
Which is best depends on your preferences. If you want or need a small saddle to bar drop, then a frame like the synapse is the better chaoice. With the BMC, you would be buying a too-big frame to get the desired bar height. Either that or you use a +6 stem instead of a -6 to gain about 20mm of bar height.
I started thinking about this route after go through the exercise of CC's fit calculator. They refer to three types of bike fit one of which being the French Fit. Are you familiar with the logic? After reading about this I started to notice the measurements on the larger sized racing geometry frame weren't too far removed from the typically "proper" sizes of the relaxed fit geometry bikes anyway. Hence, my conversation here. CC defines French Fit as:
Originally Posted by Competitive Cyclist
3. The French Fit.
This fit is so named because of its legacy in the traditions of endurance road riding such as brevet rides and randonneuring. However, the French Fit isn't merely about touring, riding long, or even sitting more upright. It is about getting the most out of a bike that fits larger and provides much more comfort to the neck, back, and saddle position.
While the Competitive Fit generally puts you on the smallest appropriate frame and the Eddy Fit sizes up a bit or raises the bars, the French Fit puts you on the largest appropriate frame. While this bucks some current conventional wisdom - and is, in fact, the least commonly used position of the three we espouse - it is still the position advocated by some of cycling's wisest and most experienced designers, who also happened to be riders who like to go fast and far with an ideal amount of comfort.
This fit features a taller front end (with a larger frame and/or head tube extension and stem), handlebar to saddle drops that are much closer to level, and favors riders who are looking to ease stress on the neck and back, ride as long and as far as they like, and are not concerned with the looking like an aggressive professional. In comparison to the Eddy Fit, the rider has even more weight rearward and a slightly more upright position such that "hands in the drops position" is close to the Competitive Fit's "hands on the hoods position." Some may say that this was not how modern race bikes were "meant" to fit but we have learned that the French Fit's size up tradition works great on the most modern bikes.
By increasing the frame size we raise the bars without radical riser stems and still create balance and proportion with respect to the important knee-to-pedal dynamic. It is important to remember that as frames get larger the top tube effectively shortens. This means that the longer top tube on a larger frame is appropriate because as the bars come "up" and the ratio of saddle to bar drop lessens, the rider achieves a "reach" from the saddle to the handlebars that is just right!
We recommend this fit for riders who really want to be comfortable and fast over longer distances. Please note that the French Fit disregards all emphasis on stand over height (standing with the bike between your legs and your shoes flat on the ground) because the French Fit school believes that this measurement has little actual value regarding fit. An ideal compromise for those who can't shed their concern regarding stand over height is the choice of a "sized up" compact design to achieve a higher relative handlebar position.
Nevertheless, a French Fit can work with traditional, non-sloping frames as well. As an example, a person who might ride a 55cm or 56cm frame to achieve the Competitive Fit, might ride as much as a 59cm or 60cm in the French Fit. While bikes in the French Fit are not the racer's fashion they tend to look elegant, well proportioned, and ride like a dream.
Is there any science to this or is it salesman voodoo?