How to Identify a Colnago C40 B-Stay HP

Colnago C40 B-Stay HP
Colnago C40 B-Stay HP
Image courtesy of Premium Cycling

This article is only part of my ULTIMATE GUIDE to the Colnago C40 which I recommend you start reading first. This guide includes a lot of information about this legendary frame such as;

  • An overview of the Colnago carbon bikes that preceded the C40.
  • The brief history of the C40 including major race wins.
  • Discussion of the C40 lugs and how the frame was assembled.
  • How to identify the different versions of the C40.
  • The different forks that were supplied with the C40 over the years.
  • Frame geometry and build specifications.


The Colnago C40 was manufactured for approximately 10 years (1994 – 2004) and over that time, 4 different versions of the frame were released. This article discusses the fourth and final version of the C40 frame, known as the C40 B-Stay HP. This model was sold for about 2 years (2003 to 2004, dates are approximate) and was superseded by the Colnago C50. Upon the release of the C50 in the 2004 catalog, the C40 was sadly moved to the back of the catalog ending it’s 10 year reign.

Why call it an HP?

According to various articles I have read, the HP stands for ‘High Power’. I was a little surprised as I expected HP to be some kind of Italian phrase; Colnago being an Italian company and all. Regardless, the diamond shape chain stays were the big change to the last iteration of the C40 frames.

These diamond chain stays are said to increase lateral rigidity while making the rear triangle more vertically compliant. which increase both the performance and comfort of the ride. Apparently Colnago engaged Italy’s Department of Aerospace Engineering (Politechnico Di Milano) to test the new diamond stay and compared to the previous C40 B-Stay frame, the HP stays increased lateral stiffness by 3.5% (for better power transmission) and provided 5% more vertical flex (to improve traction).

I find it interesting too see that these new chain stays were initially released on the C40 when it was to be shortly replaced by the Colnago C50 in 2004. An unusual case of trickle up technology or was it an attempt to gauge consumer reaction to the radical design, before releasing the new C50? The diamond stay design was eventually dropped when the Colnago C59 was released 7 years later in 2011.

General Features of a C40 Frame

All 4 versions of the C40 frame were made from carbon tubes and carbon lugs. They were not a monocoque design, which has a flowing style – like modern carbon frames. The top tube and down tube featured a distinctive 4 sided Master profile as shown in the images below. The majority of C40 frames were built using traditional geometry (that has a horizontal top tube). However from 2001, their catalog listed sloping geometry for the small frames sizes (46,47,48).

Colnago C40 frame tubes
Colnago C40 frame tubes

How to Identify the fourth (last) version of the C40 frame

Colnago C40 B-Stay HP (2004 catalog page)
Colnago C40 B-Stay HP (2004 catalog)

When trying to identify the last version of the C40 frame, you need to look at a few specific features;

1. The chain stays feature the diamond design with a cut-out on either side as shown in the catalog image above.

2. Because the C50 has very similar (but not identical) diamond chain stays, you will also need to look at the diameters of the main tubes. The C40 tubes are smaller and have a constant diameter. The top tube and down tube on the C50 are more heavily sculpted as well as larger in diameter (as you can see in the image below).

3. If you are still not sure, measure the diameter of the fork steerer. The C40 has a 1 inch diameter for all it’s models. The C50 had the new 1-1/8 inch diameter fork steerer.

Colnago C50 frame (2004)
Colnago C50 frame (2004 Colnago Catalog)

Titanium Bottom Bracket Sleeve

I believe the C40 B-Stay HP (and some late model C40 B-Stay frames) were fitted with a titanium bottom bracket sleeve to eliminate corrosion in the bottom bracket shell that was known to occur on earlier models of the C40 frame. It was also mentioned that some late model C40 frames were fitted with a replaceable rear derailleur hanger.

C40 in Sloping Geometry

Looking at the list of C40 frame sizes in the 2004 Colnago catalog (below), you can see that Colnago was selling the small sizes of the C40 B-Stay frame (46, 47, 48) with sloping geometry. Larger size frames had FREULER geometry which means the head tube and seat tube extend higher above the top tube than a regular sized frame to reduce stand-over clearance on large frames.

In 2004, the Colnago C50 was released with a wider range of frames in sloping geometry (45s, 48s, 50s, 52s) – following the new trend of compact frame design.

Colnago C40 B-Stay HP frame sizes
Colnago C40 B-Stay HP frame sizes (2004 catalog)


About Me.

I have been riding and working on my own bikes for many years now. I wanted to share my experiences, knowledge and research with others. My aim is to inspire people to get involved in all aspects of this amazing sport. Cheers.


I welcome reader feedback in the comments section. Should you wish to suggest an amendment, please include a note advising the source of your information so that myself and other readers can ascertain the accuracy of your information. Note: Trolling or argumentative comments will be removed as they are counter-productive.

Leave a Reply

Leave a Reply

Your email address will not be published. Required fields are marked *

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.