Frame geometery

Hi,

I have a frame with a 72 seat angle 57.5 top tube and 55(c-c) seat tube with
a 120 stem.

It has been suggested that a 73 seat tube with a 56.5 top tube and a 120
stem is exactly the same.

My maths is not that good, are the equivalent?

Thanks

cpm- I have a frame with a 72 seat angle 57.5 top tube and 55(c-c) seat tube
with
a 120 stem.

It has been suggested that a 73 seat tube with a 56.5 top tube and a 120
stem is exactly the same. BRBR
My maths is not that good, are the equivalent? BRBR


Essentially. General rule of thumb is as you change the seattube angle by one
degree, and moving your saddle forward or aft ro accomodate this to retain
KOPS, you move it 1cm.



Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

cpm- I have a frame with a 72 seat angle 57.5 top tube and 55(c-c) seat tube
with
a 120 stem.

It has been suggested that a 73 seat tube with a 56.5 top tube and a 120
stem is exactly the same. BRBR
My maths is not that good, are the equivalent? BRBR


Essentially. General rule of thumb is as you change the seattube angle by one
degree, and moving your saddle forward or aft ro accomodate this to retain
KOPS, you move it 1cm.



Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

the setback of the toptube and seattube intersection is cos(angle) times
seattube length. So the difference between a 72 and a 73 seat angle for a
55 C-C seattube is:

55cm * (cos(72) - cos(73)) = 0.924 cm, which is close enough to one
centimeter for your needs.

Bruce

"Colin Marshall" wrote in message
...
Hi,

I have a frame with a 72 seat angle 57.5 top tube and 55(c-c) seat tube
with
a 120 stem.

It has been suggested that a 73 seat tube with a 56.5 top tube and a 120
stem is exactly the same.

My maths is not that good, are the equivalent?

Thanks