ThermionicScott 

Probably safer to start your own thread. There's a lot more to fitting a bike than your height, so...maybe.

Chare

Ah ok thank you!

Bandera

To be crystal clear: a 4cm variance from my 56cm properly fit frame either way is unacceptable.

On a 52cm Vitus seatposts were not long enough to set my correct seat height.
That certainly compromises pedaling efficiency.
Too small.

On a 60cm Vitus setting seat height correctly is not a problem, however saddle rails are too short to properly set my cleat to pedal axle position.
That certainly compromises pedaling efficiency.
Being unable to comfortably straddle a 60cm frameset presents another aspect that should be obvious as well.
Too tall.

A Goldilocks fit gets everything Just Right, anything else is a kludge.

-Bandera

ThermionicScott 

Aren't those shortcomings of your parts, not the frames? It seems like longer or non-setback seatposts (much easier to find these days than in the past) could solve every issue except the standover on the larger frame.

Bandera

Nope, that's how the frame with it's non-sloping top tube and it's generation of components were designed to work for a Classic Road racing fit.
Too small and too large are what they are.





Converting to 'brifters, a CF saddle and a power tap would just be so wrong on this beauty as well.
Sometimes the Period Correct Police have it right.


If one desires a Modern Race fit, which I most certainly do not, select a modern frame in the proper size and contemporary component groups instead.



Buying the proper frame size as appropriate for French/Rando, Classic Race and Modern Race is just not that difficult, why kludge around if one is going to be doing high effort/long distance cycling.


-Bandera

Road Fan

I think some distinctions would be helpful and you are starting to make them. I think fitting is accomplishing what Hamilton described, to adjust the bike and its parts so that all your desired contact points and weight distribution are achieved. Sizing is to select a bike frame and its size, given its design, that lets you achieve that good fitting. Depending on design, a range of bike sizes could allow you to get an excellent fit.

Unless you are totally constrained to use a new bike exactly as you bought it, fitting and size selection are different steps in the process of getting a bike that fits well for you use.

Once you get helped with a fitting, you go out in the real world. There your body moves around as you deal with bumps, road gratings, cars, hills, live animals, dead animals, junk on the road surface, weather, fatigue, and lighting. You butt might not want to be in that perfect location all the time, or you might have a clothing malfunction that makes you change your position. Then you have adjustments to make. The fitting is just a starting point, even if it is perfect when you leave the store. But if you don't have a good sizing, the adjustments you can make to your fitting could be limited.

Road Fan

As a math Goldilocks, something here is not Just Right, though far short of a kludge.

If you have a 52 cm frame with a 73 degree seat tube angle and a 56 cm frame with a 73 degree seat angle, and you set your saddle height the same on both, the horizontal distance from the saddle rail clamp to the BB will be the same. Same for a 60 cm frame with that same angle. Hence there is no need in those three cases to change the saddle position on the seatpost. It's just trigonometry. As long as your preferred height can be achieved on all three bikes (you might be too tall for a short post on the 52 or too short to achieve target height on the 60), you pedaling should be the same on all three bikes.

If the 60 cm Vitus has a different seat tube angle, you could run out of "slide range" on a saddle.

Bandera

It's not just math, the realties of the hardware and the rider's personal requirements are in the real world and are Hard Constraints not academic abstracts.
Fitting a rider on bike properly assures that they are as comfortable, efficient and in control as possible.
Having the correct frame size matters in the process, which is tested on real hills for real hours by real riders on actual hardware not a spreadsheet.

Once more, the seatposts of the design era are Too Short to get the saddle height correct on a 52cm frame, it is simply Too Small.
Try finding a 25mm OD seatpost long enough for the suggested kludge ( good luck), if found the drop would be 9cm, not the 5cm required for a Classic Race fit as pictured.
That puts it into Modern Race fit, which I am not adapted to or interested in with decades on this very fine Guimard/LeMond system fit.

With the Classic Race fit I run DT controls, which is part of the fit design requirement for confident convenient shifting in a peloton of the era.
Try that with an extra 4cm of drop, no thanks that's Way below where I could operate. Too small, even if kludged.
Quill stems will not allow a taller position, it is what it is.

Control placement and operation is reflected in frame design for each generation of components.
The fit and sizing of the 1940', 1980's and 2000's takes into consideration control operation.



Modern Race fit relies on the 'brifter system ( with considerable seat time and adaptation),re-designed "cockpit" components and saddles to achieve the extremely aero position top riders use today.
If we still ran the Bianchi's '40's tech we'd still use a similar frame sizing from that era.
A 4cm frame size variance up/down today would be just as unacceptable as in my Classic Fit era. Ask in '33 if you are curious.

It does, you will.
The Turbo on my 56 is slammed back to max to get the correct cleat to pedal spindle, a 25mm seat post did not come w/ set back: Too Big and a big wobbly pig as well.

Rule #1 in getting a proper fit for whatever high effort/long distance cycling one does has been to get the Proper Size frame and have the components selected correctly on it.
If you think that kluding around on framesets that Just Do Not Fit is worth the time, effort and $$$$ have at it.

I wear shoes that fit and ride bikes that do too, not so great for comfort or efficiency to cut holes in the toes or shove wadded up newspaper in one's sneakers.....

-Bandera