Which size Colnago?

[phcollard]

Hey folks!

Long time no see

I'm looking to get a Colnago C-RS, my first carbon bike ever.

I'm 5' 8.5". My current bikes are a Merckx Corsa Extra and a Merckx Gara. Both have a 55cm top tube, 10cm stem and a 72.5cm saddle height. I'm 48 and have a fragile back so I'm definitely looking for a relaxed position. I run a more or less 5cm drop from top of saddle to top of bars.

I'm not sure if I should get a 52s or a 50s C-RS. Geometry here.

50s : 145mm HT, ETT 54cm, STA 74
52s : 163mm HT, ETT 55cm, STA 73.6

So on paper both sizes are very close. I have the choice to run either the 50s with a lot of spacers and a 11cm stem, or the 52s with fewer spacers and a 10cm stem.

Thoughts?

Here is a recent pic of my Merckx alloy for reference...



Cheers!

[bigbill]

Unless you're hard and fast on buying a Colnago, you could get an Allied with a taller head tube to get the reach you want without a bunch of spacers. Made in Murica.

[phcollard]

Originally Posted by bigbill

Unless you're hard and fast on buying a Colnago, you could get an Allied with a taller head tube to get the reach you want without a bunch of spacers. Made in Murica.

Thanks. I had never heard of the brand so I took a brief look. They look great and made in USA is definitely an advantage. But frameset at $3k vs complete Colnago at $1.2k is a no brainer.

[bigbill]

Originally Posted by phcollard

Thanks. I had never heard of the brand so I took a brief look. They look great and made in USA is definitely an advantage. But frameset at $3k vs complete Colnago at $1.2k is a no brainer.

Allied was partially formed from Guru when they closed. Then the Colnago needs to have the right tt length with a 110 stem. I've had some back surgeries, my bikes have long head tubes.

[oldpotatoe]

Originally Posted by phcollard

Hey folks!

Long time no see

I'm looking to get a Colnago C-RS, my first carbon bike ever.

I'm 5' 8.5". My current bikes are a Merckx Corsa Extra and a Merckx Gara. Both have a 55cm top tube, 10cm stem and a 72.5cm saddle height. I'm 48 and have a fragile back so I'm definitely looking for a relaxed position. I run a more or less 5cm drop from top of saddle to top of bars.

I'm not sure if I should get a 52s or a 50s C-RS. Geometry here.

50s : 145mm HT, ETT 54cm, STA 74
52s : 163mm HT, ETT 55cm, STA 73.6

So on paper both sizes are very close. I have the choice to run either the 50s with a lot of spacers and a 11cm stem, or the 52s with fewer spacers and a 10cm stem.

Thoughts?


Cheers!

52 with longer headtube..

[phcollard]

Originally Posted by oldpotatoe

52 with longer headtube..

Thanks very much OP. That what I'm leaning towards...

[Dave]

Don't overlook the difference in the STA. With the steeper STA on the 52, you're likely to need a 90mm stem, once the saddle is moved to the same position, relative to the bottom bracket.

Oops, I now realize that the 72.5 was saddle height, not STA, but without the STA to compare, you can't know what stem length is needed.

[oldpotatoe]

Originally Posted by Dave

Don't overlook the difference in the STA. With the steeper STA on the 52, you're likely to need a 90mm stem, once the saddle is moved to the same position, relative to the bottom bracket.

But Merckx's he has probably has STA of 73.5..so very close to the 52cm Colnago.

[phcollard]

Originally Posted by oldpotatoe

But Merckx's he has probably has STA of 73.5..so very close to the 52cm Colnago.

That's correct. Merckx has an STA of 73.5

That blue Merckx of mine has a HT length of about 160mm.

I found this geo comparator. 50s and 52s have the same reach apparently. Not sure what it means!

[wallymann]

as others have suggested, focus on STA + TT length to pick your comparable size.

[Dave]

Reach is the horizontal distance between the center of the BB and the center of the head tube. If the reach is the same on two frames, the stem length needed should be the same.

https://rideonmagazine.com.au/how-to...ack-and-reach/

LOOK gets it. The 785 reach increases by 10mm for each size.

[m4rk540]

Originally Posted by bigbill

Unless you're hard and fast on buying a Colnago, you could get an Allied with a taller head tube to get the reach you want without a bunch of spacers. Made in Murica.

If a Colnago head tube isn't tall enough, one should rent a time machine, go back to 2005 and order a Serotta.

[weisan]

Or a Giant.

[paredown]

I don't have an opinion on your sizing, but I have been watching the clearance on the CR-S, so I will be curious to see what you think.

FWIW--as a general comment, what I read made me think these are a little bit less a cheaper version of an all out race bike, and a little more of a comfort fit, whereas the last time around with the ACR, it was more the former.

[oldpotatoe]

Originally Posted by weisan

Or a Giant.

A Giant rather than a Colnago for $1200?..righto..in yer dreams, pal..