[some_guy282]

I've got a 2004 Trek 4500, and I'm upgrading the seatpost. I measured the diameter myself and came up with about 4 inches and used google to convert it to millimeters and came up with... 101.6mm!? I guess I did something wrong.

Anyway, does anyone know the diameter on the seatpost, or how I can accurately measure it myself?

 

[fireball]

I've got a 2004 Trek 4500, and I'm upgrading the seatpost. I measured the diameter myself and came up with about 4 inches and used google to convert it to millimeters and came up with... 101.6mm!? I guess I did something wrong.

Anyway, does anyone know the diameter on the seatpost, or how I can accurately measure it myself?

the diameter should be stamped on the seatpost just below the min. insertion line.

 

[some_guy282]

the diameter should be stamped on the seatpost just below the min. insertion line.

Found it. Thanks.

 

[avsb514]

I have a 4300 and the post is 31.6 mm i think. It's twards the bottom for the seatpost if you pull it completely out.

 

[tlg]

I've got a 2004 Trek 4500, and I'm upgrading the seatpost. I measured the diameter myself and came up with about 4 inches and used google to convert it to millimeters and came up with... 101.6mm!? I guess I did something wrong.

Anyway, does anyone know the diameter on the seatpost, or how I can accurately measure it myself?

Ahhh you were close young greasshopper. 4" is the circumference. So using some elementary geometry:
Circumference = PI x Diameter
Therefore,
Diameter = Circumference divided by PI
= 4" / 3.14159
Diameter = 1.273"

The metric conversion from inches to mm is 25.4. 1.273 x 25.4 = 32.33mm

You probably have a 31.6mm seatpost. 31.6/25.4= 1.244"
1.244" x 3.14159 = 3.908" Cir. Pretty close to your 4".

 

[some_guy282]

Yup, it's 31.6. Thanks guys.