Modern group on a C40?

[malley]

Can I fit a modern compact group on my colnago C40?
I am thinking about bb width? The height of the front derailleur hanger? Italian threads?

Thinking of a black 105 group. I know!

Also on the look out for a Colnago star fork with a long steerer .

Cheers.

 

[mattr]

Only issue is the height of the front mech hanger. Hangers of that era are usually geared up around 52-55 tooth rings. So you'll *possibly* not get it quite low enough. I have the same issue using a 36/50 on a mid 90's steel bike of mine. Still works far better than the 10 speed it replaced, despite being too high. Some are ok though depends on the initial build of the frame.

C40 isn't old enough to be 126mm OLN and IT threaded bottom brackets (even in 105 11 speed flavour) are still widely available.

 

[mattr]

And a chromed finish groupset would look much nicer.

 

[james_from_stoke]

if you're having 105, have the silver one

 

[malley]

Re:

Thanks for these. I hear you ref silver gruppo.

So, is the front mech the main issue?

 

[hamster]

The problem is the drop from the braze-on front mech hanger for the small compact chainrings. Switch to a 38/52 or similar size chainset on the front and it will fit trouble-free.

 

[NeilM]

Re:

I say give it a try.

I recently experimented with replacing a 50/34 chainset with 46/36. The mech hanger meant that the front mech was as low as it would go, which was a little high for the 50 tooth chainring.

So far I have had absolutely no issues. :shock:

 

[mattr]

Yeah, if you go to a 52 big ring it'll be within tolerance. 50 is *just* out.

But, if you have the bike already built up, trial fit a new front mech, and see how low it will go. A 50T big ring will be about 10 or 11 mm smaller diameter than a standard 53T, so about 4-5 mm on radius. If you can get an 11 speed front mech 5 mm too low, you'll be fine, get a 50. If not, either live with some slight niggles, or get a 52/53 big ring.......

 

[mattr]

Re: Re:

I say give it a try.

I recently experimented with replacing a 50/34 chainset with 46/36. The mech hanger meant that the front mech was as low as it would go, which was a little high for the 50 tooth chainring.

So far I have had absolutely no issues. :shock:

Yeah, it is very dependant on frame, groupset, build tolerances, cassette size, gears you tend to use and what you define as "no issues".

The 10 speed compact i had on before worked ok, but used to rub a bit more than i'd like and the trim wasn't spot on, no matter how it was adjusted.
The 11 is better.

I'll still switch to a 52 or 53 big ring at some point, or an oval. Which potentially causes yet more issues!

 

[bikenrrd]

Re:

You can get 105 chainsets (and most other modern groupsets) in 53-39, 52-36 and 50-34 chainrings. With 11 sprockets available in 11-32 and 11-28, you can get a good spread of gears with not too large a jump between the gears.

I'd try 52-36 chainrings with 11-28 cassette. This gives approximately 35 inch bottom gear, which is lower than the usual 25 or 26 sprocket used on a 50-34 compact chainset.