How to Identify a Colnago C40 B-Stay

Colnago C40 B-Stay bicycle
Colnago C40 B-Stay – Third Version of the Colnago C40 frame
Image courtesy of Speed Bicycles

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 third version of the C40 frame, known as the C40 B-Stay. This model was sold for about 3 years (2001 to 2003, dates are approximate).

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 in 2001, their catalog listed sloping geometry for the small frames sizes (46,47,48).

Colnago C40 frame tubes
Colnago C40 frame tubes
Colnago C40 B-Stay top tube
Colnago C40 B-Stay top tube with Master Profile shape.
Image courtesy of Speed Bicycles

The C40 logo was located at the top of the seat tube as shown in the following image.

Colnago C40 B-Stay seat tube
Colnago C40 B-Stay seat tube.
No Colnago Ace of Clubs featured on this seat tube.
Image courtesy of Speed Bicycles

How to Identify the 3rd Version Frame

2001 Colnago C40 B-Stay catalog page
2001 Colnago C40 B-Stay catalog page

It’s simple to identify the third version of the C40 frame, just look for these 2 features;

1. The seat stays are a bulkier design (usually labelled B-Stay) than the previous 2 versions of the C40 and they originate from a single point on the seat post lug as shown in the diagrams below. On earlier versions of the C40 frame, the seat stays are 2 seperate pieces.

2. Next look at the chain stays. The 3rd version of the C40 frame has regular looking chain stays whilst the 4th version of the frame was built with distinctive triangular HP chain stays. Please refer to the image of the regular chain stays below. Images courtesy of Speed Bicycles.

Colnago C40 B-Stay chain stays
Colnago C40 third version features regular chain stays.
Image courtesy of Speed Bicycles

C40 in Sloping Geometry

Looking at the list of C40 frame sizes in the 2001 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).

2001 Colnago Catalog C40 frame sizes
2001 Colnago Catalog C40 frame sizes

Change in Rear Brake Cable Routing

The first 2 versions of the C40 frame featured 3 x brake cable guides on the top tube. The rear brake cable outer was run all the way to the rear brake. However, with the B-Stay frame, there are now 2 x brake cable stops/guides on the top tube. The outer casing no longer runs all the way to the rear brake. The brake cable is now exposed in the middle section of the top-tube to reduce friction and save weight.

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.

2 thoughts on “How to Identify a Colnago C40 B-Stay

  • Hi..i just bought of the BSTAY frame with chrome lugs/forks..and just want to justify the model/spec of this COLNAGO MASTER B-STAY frame

    • Hi Zaki, your frame has chrome lugs? That sounds like you have a steel frame. Colnago make a steel frame called the Colnago Master.
      Have a look at this article How to identify a Colnago Master.

      The bike in this article is a Colnago C40 which has a carbon fibre frame and lugs. This model features ‘B-stay’ design rear seat stays.

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