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sizing by c-t????(11 posts)

sizing by c-t????colker
Nov 15, 2001 4:07 PM
i know the c-s routine but... what's the formula for c-t? (trying to size a colnago..)
thanks
Colnago C40 B-Stay + Free Campagnolo Carbon Crank + WheelsetPrince
Nov 15, 2001 6:32 PM
Hi Colker

Here is the formula.

0.67 x Inseam Length (cm) = C-T Bike Frame Size.

Note one thing about Colnagao their top tube is relatively short.

It could that relative to your legs you may have longer or shorter torso and arms. So even though you have the correct bike size (seat tube length), the top tube can sometimes be to long or short.

So sometimes with Colnago because of the shorter top tube you may have to fit the bike using top tube length.

This is the formula to size top tube length ;

(Torso Length + Arm Length) / 2) + 4  = ( Top Tube + Stem)

Note three important thngs about fitting Colnago ;

1.

If the seat tube length gives you the right top tube length + stem length then fine use 0.67 x inseam.

Go ahead and buy a Colnago C40 from me, contact me at ItalianBikes@mac.com and I'll give you the most unbeliavble of offers.

2.

Having used the above two formulas ;

A. Seat Tube ;

0.67 x Inseam Length (cm) = C-T Bike Frame Size.

B. Top Tube + Stem Length ;

(Torso Length + Arm Length) / 2) + 4  = ( Top Tube +
Stem)

and the top tube is too long then what you have to do is buy a frame with the correct top tube + stem length.

The top tube can be longer because you have relatively
shorter torso and arm length.

This will mean a slighlty smaller Bike Size (Seat Tube Length).

This will give you the correct top tube + stem length.

However, the seat tube length will be to short for you.

Since you want the correct seat tube length i.e. Correct Bike Size, you will have to use a 350mm 27.2mm Campagnolo Carbon Seat Post, this extra long seatpin will give you back the cm that you lost in sizing the top tube. ie gives you a longer seat tube length.

The Colnago Carbon seat post is 28mm, what you have to do is insert a 0.8mm metal tube into the Seat Tube.

How high will this seat post be ?

Work out what your bike size = 0.67 x Inseam Length.

The difference between the bike size (0.67 x Inseam length) and the seat tube length is how much Seat Post Length you have to add to the seat tube. This gives you the correct total Seat Tube Length.

For example, you size is 56cm C-T the seat tube is 54cm to give the shorter top tube. You are short of 2 cm in the seat tube so just add 2cm of seat post length (insert the seat post into the seat post and just bring it out 2cm) .

Note you will have to use this as the base for adjusting the Saddle Height (0.883 x inseam length) with the additional 2cm.

However, in most cases the stem length can take care of this problem. But for a minority of people they would have to pursue the above method.

3.

If the top tube length is to short. Use the Top Tube + Stem length formula to get the correct top tube length for your torso and arm length. This could be because you have relatively longer torso & arm length and relatively shorter legs.

This will give you a longer seat tube, but because you have to fix saddle height at 0.883 x Inseam length, this will give you a relatively shorter saddle height ( relative to seat tube), you will be well within your saddle height even though your seat tube length is longer.

For example your .67 x Inseam gives you a size of 54cm

this bikes top tube length doesn't fit you.

You have decided to go with a 56 cm Size Seat Tube Length because this size gives you the right top tube length to fit your long torso and arms. However this might give you a seat tube length of 58cm.

4cm more than required.

But because your saddle height is 0.887 x Inseam = 71.4 cm this is still longer than the seat tube length of 58 cm. So this bike will fit you no problem.

Note one important factor when you adjust up and down top tubes like this. This can change your SADDLE TO STEM DROP. No problem. You can raise the handlebars up or down into the correct position by using Spacers. You can increase the bar height by 5 inches or 11 cm.

Did you get all that ?

Good.

It is always a trade of between Seat Tube and Top Tube. Depending on your relatively shorter or longer torso arm and leg lengths.

If you are going to buy a Colnago C40 or CT1 buy from me. Contact me at ItalianBikes@mac.com and I'll give you the most unbeliavble of offers.

Even if you don't buy from me let me kow how you find this information and how you get on. You can post a reply to this message or just email us.

One last thing don't go into a bikeshop to buy a Colnago buy having the salesguy getting you to stand next to the bike. This will be disastrous.

REMEMBER REMEMBER

Ever saw a 6' guy with a long torso and short legs ?
Ever saw a 6' guy with short torso and long legs ?
Ever saw a 6' guy who is between those two ?

Ever saw a 6' guy with a long torso, short legs and really really long arms ?

Yes you have. It's the guy at the cycling club who humiliated you. Quick throw him a banana.

Yours truly

ItalianBikes@mac.com
thanks, tried your email but didn't work!colker
Nov 16, 2001 12:51 PM
thanks for all the info man! tried your formula and found out i have the body proportions of a gorilla. a thin, light gorilla but my torso and arms ask for a much bigger frame than my inseam. i like the concept of satndover clearance so a short top tube design doesn't make much sense for me. i should try to find a ciocc or another long bike.
don't know why but i can't reach you email address.
Colnago C40 B-Stay + Free Campagnolo Carbon Crank + WheelsetPrince
Nov 16, 2001 3:50 PM
Hi Flavio

This is Euston, we copy you on the ground !

Get this.

0.67 x Inseam = Bike Size C-T

0.67 x 81.5 cm = 54.6 cm = Rounded Up = 55 cm C-T / Seat Tube Length

A Colnago 55cm C-T seat Tube equates to a 54.3 cm Top Tube.

If your "cockpit" length is 68 cm this means that the difference of "Cockpit Length 68cm - Top Tube Length 54.3cm = Stem Length 13.7 cm

The Colnago C40 comes with the Colnago ITM Stem.

The ITM stem comes in lengths from 9 cm to 14 cm.

Since you need only an additional 13.7 cm cockpit length, you will need a 14 cm stem.

You can just about fit. So relax your not yet a gorilla.

Your saddle height is 0.883 x Inseam 81.5 cm = 72 cm ( 55 cm Seat Tube + 17 cm Seat Post Length. )

For later, note that your seat post length is 17 cm

goog noos ?

Ha ?

Note one very important thing when fitting any bike, if you buy a frame which is exactly your size, then this will be a tight fit. You should always buy a frame slightly bigger than your actual bike size, because this gives you a more comfortable fit.

Do you know that you can even have a 9 cm Stem and 59 cm Top Tube (Cockpit length 68 cm - 9cm Stem Length = 59 cm top Tube Length)

A Colnago with a 59 cm Top Tube has a 64 cm Seat Tube.

Since your saddle height is 72 cm (Your saddle height is 0.883 x Inseam 81.5 cm = 72 cm) and the Seat Tube is 59 cm. This means that the Seat Post length is 13cm (72 cm saddle height - 59 cm Seat Tube Length.)

How you noticed anything ?

The 55 cm bike gave you a Seat Post Length of 17cm

Seat Tube Length of 55cm

Saddle Height of 72 cm

Top Tube Length 54.3cm

Stem length 14 cm

Cockpit length 68.3

The 64 cm bike gives you a Seat Post Length of 13cm

Seat Tube Length of 64cm

Saddle Height of 72 cm

Top Tube Length 59cm

Stem length 9cm

Cockpit Length 68 cm

With a 68 cm cockpit length

you can have a longer stem 14 cm and a shorter top tube 54.3 cm

or you can have a shorter stem 9 cm and a longer top tube 59 cm

either way note how your cockpit length remains the same at 68 cm.

With a 72 cm Saddle Height

you can have a longer seat post 17 cm and a shorter seat tube 55 cm

or you can have a shorter seat post 13 cm and a longer seat tube 64 cm

either way note how your saddle length remains the same at 72 cm.

Did you get all that ?

No you didn't.

For all this to sink in you'll need an hour or two.

Let me know how you get on.

Over and out.

ItalianBikes

Make sure you take proper measurements
ActuallyCT1
Nov 16, 2001 6:22 PM
The smaller Colnago frames (<53cm) have longish tt's.

I think Ernesto is whacked when it comes to small and large frame sizes.

JohnG
go by STANDOVER HEIGHT!!!NFM
Nov 16, 2001 6:13 AM
NFM
hey Colkergtx
Nov 16, 2001 11:31 AM
just measure your current bike c-t, then see what Colnago that would be. Then compare the tt length and seat tube angle on that size Colnago to your bike and see if it will work for you. Maybe go up or down a size (which is really a half size if you are comparing to a c-c bike) depending on tt length. For example, I usually ride a 57 c-c. I'd look at the 58 or 59 Colnagos (roughly 56.5 c-c and 57.5 c-c). Good luck.

-Hank
hey Colkercolker
Nov 16, 2001 12:46 PM
don't know if a colnago will fit me..i took some torso and arm measures. my top tube + stem is roughly 68cm!
i'm riding a c-c 54cm with a 13cm stem! i tried a 12cm and an 11cm but the 13 is the one i feel comfortable.
that's why i could never find the perfect mtn bike frame! my inseam would say 17in but my torso needs a 19in.
i should either find a ciocc (never even saw one around here), talk to brent steelman to build me a custom or buy a modern 54cm pinarello (there's lots of oinarellos and cinellis here) and install another 13cm stem.
i do prefer the handling, cornering etc.., with an 11cm stem though..
Colnago C40 B-Stay + Free Campagnolo Carbon Crank + Wheelset  PrPrince
Nov 16, 2001 3:53 PM
Hi Flavio

This is Euston, we copy you on the ground !

Get this.

0.67 x Inseam = Bike Size C-T

0.67 x 81.5 cm = 54.6 cm = Rounded Up = 55 cm C-T / Seat Tube Length

A Colnago 55cm C-T seat Tube equates to a 54.3 cm Top Tube.

If your "cockpit" length is 68 cm this means that the difference of "Cockpit Length 68cm - Top Tube Length 54.3cm = Stem Length 13.7 cm

The Colnago C40 comes with the Colnago ITM Stem.

The ITM stem comes in lengths from 9 cm to 14 cm.

Since you need only an additional 13.7 cm cockpit length, you will need a 14 cm stem.

You can just about fit. So relax your not yet a gorilla.

Your saddle height is 0.883 x Inseam 81.5 cm = 72 cm ( 55 cm Seat Tube + 17 cm Seat Post Length. )

For later, note that your seat post length is 17 cm

goog noos ?

Ha ?

Note one very important thing when fitting any bike, if you buy a frame which is exactly your size, then this will be a tight fit. You should always buy a frame slightly bigger than your actual bike size, because this gives you a more comfortable fit.

Do you know that you can even have a 9 cm Stem and 59 cm Top Tube (Cockpit length 68 cm - 9cm Stem Length = 59 cm top Tube Length)

A Colnago with a 59 cm Top Tube has a 64 cm Seat Tube.

Since your saddle height is 72 cm (Your saddle height is 0.883 x Inseam 81.5 cm = 72 cm) and the Seat Tube is 59 cm. This means that the Seat Post length is 13cm (72 cm saddle height - 59 cm Seat Tube Length.)

How you noticed anything ?

The 55 cm bike gave you a Seat Post Length of 17cm

Seat Tube Length of 55cm

Saddle Height of 72 cm

Top Tube Length 54.3cm

Stem length 14 cm

Cockpit length 68.3

The 64 cm bike gives you a Seat Post Length of 13cm

Seat Tube Length of 64cm

Saddle Height of 72 cm

Top Tube Length 59cm

Stem length 9cm

Cockpit Length 68 cm

With a 68 cm cockpit length

you can have a longer stem 14 cm and a shorter top tube 54.3 cm

or you can have a shorter stem 9 cm and a longer top tube 59 cm

either way note how your cockpit length remains the same at 68 cm.

With a 72 cm Saddle Height

you can have a longer seat post 17 cm and a shorter seat tube 55 cm

or you can have a shorter seat post 13 cm and a longer seat tube 64 cm

either way note how your saddle length remains the same at 72 cm.

Did you get all that ?

No you didn't.

For all this to sink in you'll need an hour or two.

Let me know how you get on.

Over and out.

ItalianBikes
hey Colkergtx
Nov 16, 2001 6:24 PM
yeah, I think an 11cm stem is ideal. And yeah, I don't think Italian bikes are going to work for you. Two stock bikes I can think of that might work ok are Ibis and Hampsten. Otherwise, yeah, I'd call Steelman or your old buddy Mikklesen.

http://www.ibiscycles.com/products/bikes/road/sonoma/geometry/

http://www.hampsten.com/pro.html
re: sizing by c-t????CT1
Nov 16, 2001 6:27 PM
Simple answer is the difference is 1.8cm between CC and CT.

The complicated answer is that you have to take seat tube angle into the equation to really understand the equivalent TT length. The TT length is ONLY part of the whole sizing issue.

****Colnagos have relatively long TT's for their small frames and relatively short TT's for their large frames. For Sizes 54-57 they are pretty much "normal".

YMMV
JohnG