# Colnago Frame sizes



## MERAKMAN (Mar 6, 2008)

Hi all

Looking at the correct frame size for me on a Colnago C50. Bio Racer measurements done at LBS are 56cm seat tube, 557cm top tube (with 11.7cm stem) with 76cm centre of bb to top of saddle. I'm 5ft 11" with inside leg measurement of 83cm. Which size C50 sounds right for me? The 57cm looks right, but I've been told that a 56cm (with 55cm top tube) would be more suitable for my leg length. Do I trust the recommendation or the Bio-Racer measurements? Thanks.


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## terry b (Jan 29, 2004)

MERAKMAN said:


> Hi all
> 
> Looking at the correct frame size for me on a Colnago C50. Bio Racer measurements done at LBS are 56cm seat tube, 557cm top tube (with 11.7cm stem) with 76cm centre of bb to top of saddle. I'm 5ft 11" with inside leg measurement of 83cm. Which size C50 sounds right for me? The 57cm looks right, but I've been told that a 56cm (with 55cm top tube) would be more suitable for my leg length. Do I trust the recommendation or the Bio-Racer measurements? Thanks.


I'm 5'11" with an 85ish inseam. I have three Colnagos, two 57's and a 58. Both work just fine, although I prefer the sizing on the 57 by a hair. I ride with my saddle at 755 and I use 120 stems. I think you would be fine on either size.


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## MERAKMAN (Mar 6, 2008)

terry b said:


> I'm 5'11" with an 85ish inseam. I have three Colnagos, two 57's and a 58. Both work just fine, although I prefer the sizing on the 57 by a hair. I ride with my saddle at 755 and I use 120 stems. I think you would be fine on either size.


Hi thanks, it does sound like the 76cm saddle height the Bio Racer said I required is a touch too high, if you have a longer inseam than me and you have a saddle height at 755...

Do you think a 56cm C50 would be too small for me? They have a 55cm top tube. I've seen a gorgous 56cm C50, but would rather not get it if its not the right size...


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## Fignon's Barber (Mar 2, 2004)

I think the size 56 would be a shade too small. that's the size I ride, and I'm 5' 10.5", inseam of 81.5 cm. I use a setback campag post, with the seat pushed back to the max. Ideally, I would think you would want a size 57. Its alot of money to spend, so get the size right the first time. Don't settle for what's in stock.


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## terry b (Jan 29, 2004)

MERAKMAN said:


> Hi thanks, it does sound like the 76cm saddle height the Bio Racer said I required is a touch too high, if you have a longer inseam than me and you have a saddle height at 755...
> 
> Do you think a 56cm C50 would be too small for me? They have a 55cm top tube. I've seen a gorgous 56cm C50, but would rather not get it if its not the right size...


I thought that 760 was on the high side for you. I experimented with that height once based on the recommendation of a fit calculator and it put me right at the edge of rocking hips when pedaling. Not good. At 755, I have the slightest bend in my knee when my leg is extended, and it feels "right".

A 56 would possibly work too, Colnago sizes are close particularly considering the top tube length. But you also have to consider the head tube - will you be able to get your bars to the proper height with the shorter head tube? It's almost a full centimeter shorter and that could make for a lot of spacers. I'm sure I could squeeze myself onto a 56, with a 130mm stem but the head tube would be the deal breaker and I'm positive that the bike would feel small.

I'd try to overcome the desire to buy a 56 because it's available and focus on a 57 which I think would be just right.


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## bertoni (Jan 10, 2008)

+1 on the headtube height concern by terry. I ride a size 55 C40, and probably should be riding a 56. I am 5'10, with shorter legs and a long torso. I have the seat shoved back quite a bit, and am able to get in a comfortable position. One thing I do like about the smaller size is that the seat tuble angle favors my femur length. I could go with a longer stem but I like where the bars are at now, provided my lower back hangs in there. The only way to know for sure is to ride both sizes. I ended up with mine from an Ebay seller who was selling the 55 and a 57. I guess he figured out that he needed a 56.


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## MERAKMAN (Mar 6, 2008)

Thanks guys, I'm testing a friends C40 at the weekend in a size 57cm, hopefully that will shed some light. The guy who recommended the 56cm actually said I needed a a 73-73.5cm saddle height! When I rode my saddle at 74cm I used to get bad cramp, hence the move to 75cm, then 76cm. Though as mentioned by Terry, I think its a tad too high too. Think I'll try it at 75.5, then 75cm. 

I've also seen a 54cm slope EP (56.5cm top tube) which I really like, do you think its a touch too far this time? What about a CX1, now I'd only have two choices with that frame, a 52cm slope (55cm top tube) or a 54cm (top tube 56cm), would I go with the larger size of the two with that one? I really want a Colnago but really need to get the right size, because, as Fignon says, its alot of money to not get the right one...


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## bertoni (Jan 10, 2008)

Are you sure your inseam measurement of 83cm is correct? Using the Rivendell sizing chart that would put you at a saddle height at 73 to 73.5. Make sure the measurement is to your pubic bone, not your pants inseam height. My inseam is exactly 83 centimeters, my saddle height is exactly 73 cm and I am only 5'10" with stubby legs. I would make sure your measurements are right before going any further.


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## mriddle (Nov 16, 2005)

*I ride a 54 sloping C-50 which = a 58 traditional*

I am 6 feet exactly, my saddle is 75.5.
Fits wonderfully. Stem is 120.
Its great that you can ride a friend's C-40 and test for size.
Good luck.


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## MERAKMAN (Mar 6, 2008)

bertoni said:


> Are you sure your inseam measurement of 83cm is correct? Using the Rivendell sizing chart that would put you at a saddle height at 73 to 73.5. Make sure the measurement is to your pubic bone, not your pants inseam height. My inseam is exactly 83 centimeters, my saddle height is exactly 73 cm and I am only 5'10" with stubby legs. I would make sure your measurements are right before going any further.



Sorry where should I measure to? Not the top of my inside leg?


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## MERAKMAN (Mar 6, 2008)

mriddle said:


> I am 6 feet exactly, my saddle is 75.5.
> Fits wonderfully. Stem is 120.
> Its great that you can ride a friend's C-40 and test for size.
> Good luck.


Hi Mriddle

How long is your inseam leg measurement (from the pubic bone :thumbsup: )?


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## bertoni (Jan 10, 2008)

How to measure your Pubic Bone Height (PBH)

a. Stand in bare feet on a hard floor.

b. Put your feet 10 inches apart.

c. Hook the edge of a metal metric tape over a thin edge -- two rulers, or a thin hardcover book.

d. Pull the tape up hard against your pubic bone. We tell folks, "Try to lift yourself off the ground

e. Have a friend take reading as you do this.

PBH ManDo this twice, thrice, or a hundred times. As long as the tape is straight and the guy reading the number knows how to read a tape, you should record the highest of all the readings you get. Why not the average? Because you'll never pull past the bone, so you can't get a reading that's too high.

It's really good to know your PBH, because from it you can determine saddle height (SH). Here's the formula: PBH - 10 to 10.5cm = SH*

*from center of the crank to the top of the saddle.

NOTE: if you're among the folks who are more comfortable with multiplication than you are with subtraction, here's a formula the formula you've been looking for your whole life long: PBH x 0.883= SH. That will be within 4mm of it, and that's good enough.

Are there ever any exceptions to the formula?
Not really, no. Sometimes mountain bike riders and cyclo-cross racers prefer a slightly lower saddle--maybe PBH minus 11.5, but it may be more out of habit. BMXers often ride PBH minus 20 or so, but that's another world.

Now and then a tiny-footed woman will do better using a SH that's 11.8cm less than her PBH.

And, if you ride 180mm cranks, you might factor that into it, too, and go with PBH minus 11 or 11.5.

If you pedal in elevator shoes, you'll need the saddle higher, so a PBH minus 8 might be better.

For the rest of us wearing shoes with normal thickness soles, PBH minus 10 to 11 is a good saddle height.


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## MERAKMAN (Mar 6, 2008)

bertoni said:


> How to measure your Pubic Bone Height (PBH)
> 
> a. Stand in bare feet on a hard floor.
> 
> ...



Thanks, so thats why the chap who measured me on a jig told me my saddle height was 73cm, though I was wearing jeans and boxers at the time, which I reckon add at least 1-2cm. Girlfriend, I have a job for you girl !

BTW How do you rate the Bio Racer method of measuring suitable frame size?


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## bertoni (Jan 10, 2008)

I neglected to mention that this was taken from the Rivendell Bike website which has a lot of good information on fitting and sizing frames. Another good site with a little different approach to frame sizing is Bike Tech by Dave Moulton. I have not used this but it seems to be regarded highly as well. Might be good to use as a means of verifying the other method.

BTW, I hope your girlfriend isn't angry with you right now, as this proceedure could hit you where it hurts!


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## MERAKMAN (Mar 6, 2008)

bertoni said:


> I neglected to mention that this was taken from the Rivendell Bike website which has a lot of good information on fitting and sizing frames. Another good site with a little different approach to frame sizing is Bike Tech by Dave Moulton. I have not used this but it seems to be regarded highly as well. Might be good to use as a means of verifying the other method.
> 
> BTW, I hope your girlfriend isn't angry with you right now, as this proceedure could hit you where it hurts!


Actually, she did that once to me by accident (so she said ) Its unbelievable how that can bring a grown man down to his knees instantly  !

Back to frame measuring and how do you rate the Bio Racer form of measuring bike frames?


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## MERAKMAN (Mar 6, 2008)

mriddle said:


> I am 6 feet exactly, my saddle is 75.5.
> Fits wonderfully. Stem is 120.
> Its great that you can ride a friend's C-40 and test for size.
> Good luck.


Thanks, could I ask you what your inseam measurement is if you know it?


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## bertoni (Jan 10, 2008)

I am not as familiar with Bio Racer as I am with Fit Kit. I am assuming they are similar, where a number of measurements are taken, as well as some attempt to factor in your overall fitness and flexibility. The fit kit device used to measure inseam does get "up there" to allow for a an accurate measurement. The overall experience of the LBS staff doing the actual fitting is as important as the measurement system itself. I would be a little concerned if they are not able to get an accurate reading for you to base your saddle height on.


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## MERAKMAN (Mar 6, 2008)

bertoni said:


> I am not as familiar with Bio Racer as I am with Fit Kit. I am assuming they are similar, where a number of measurements are taken, as well as some attempt to factor in your overall fitness and flexibility. The fit kit device used to measure inseam does get "up there" to allow for a an accurate measurement. The overall experience of the LBS staff doing the actual fitting is as important as the measurement system itself. I would be a little concerned if they are not able to get an accurate reading for you to base your saddle height on.


Are we talking about the measurement taken standing feet apart on a wooden platform, back againast a wooden backing, with a horizontal metal pole shoved up into your crouch? It definatly was 'up there' as I recall! Couldn't have got any further up there, or I would now be a paid up Opera singer 

So the results of such a test are reliable enough to base buying a frame size on would you say?


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## bertoni (Jan 10, 2008)

That is indeed the measurement for inseam. And they got a measurement of 83cm?
You must have a long trunk. I would be looking at a minimum frame size of 57 on a Colnago since the top tubes run a little shorter, and that would get the head tube up a little higher. Of course ymmv. I would also double check your saddle height, which seems a little high for your inseam.


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