Two techie Serotta questions...

[pubdef]

that I am a tad embarrassed to ask, but here goes:

1. What exactly is "Colorado Concept" tubing?

2. What is the difference between the Coeur dAcier frame and the steel Fierte frame from the year when they both had carbon seatstays? Is it just geometry and custom vs. stock? Or this tubing and/or construction somehow different?

Thanks in advance...

[oliver1850]

Colorado Concept tubing is tapered, larger diameter at one end (BB) than the other.

I think the CDA is Colorado Concept, while the Fierte is round Columbus. The CDA was available as a custom (maybe only as a custom), but I think the Fierte was only sold in stock sizes.

Take a close look at the descriptions in the 2005 catalog, you may find some other details.

[Ken Robb]

Serotta would refer to different tube sets as C2, C3, C4 and C5 though I think that C5 might have only been available in ti.

A CDA was C4 while I think Fierte was C2. The numbers referred to how many of the frame's tubes were Colorado Concept. Ben described the idea as being like a tree: bigger diameter at the bottom where there is the most stress and tapering toward the top where maximum stiffness was not needed and weight could be saved.

[oliver1850]

I went back and looked at the specs chart in the 2005 catalog. The Fierte used P2S tubeset, which had a Colorado downtube only. It was not available in custom sizes.

The CDA used the C5S/C5 tubeset and had Colorado down, seat, and top tubes.

Specs may have been slightly different in other years.

[Mark McM]

Ben described the idea as being like a tree: bigger diameter at the bottom where there is the most stress and tapering toward the top where maximum stiffness was not needed and weight could be saved.

Which makes a lot of sense. Tapered tubing was already widely used for fork blades and chainstays (and for the same reasons), why not extend the concept to the main frame tubes as well? The recent trend toward tapered steerers is also part of this concept.

[Ti Designs]

The CDA was available as a custom (maybe only as a custom), but I think the Fierte was only sold in stock sizes.

At the request of a few shop guys, they did offer a custom version of the Fierte. The first batch was called the Chimera but the name was changed to La Corsa before they printed the '06 catalog.