# Mountain Biking - How to measure my bikes frame?

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View Full Version : How to measure my bikes frame?

Trek6500ZX
07-19-03, 12:40 AM
Hi, I am just wondering how I go about measuring my bikes frame? Thanks!

tFUnK
07-19-03, 12:45 AM
what i do:

seat tube: center of crank to either the middle of the top tube where it meets the seat tube (c-c), or center of crank to the top of seat tube (c-t).

top tube: measure the length of the top tube end to end but measure from the center where it meets the seat and head tubes, not where it directly meets them. on bikes with v-shaped top tubes i measure across from where the tube meets the head tube to where it meets the seat tube, but again, i measure the center, not the junction edge.

Trek6500ZX
07-19-03, 01:01 AM
Ok, I edited a picture to make sure I understood what you were explaining:

Jim311
07-19-03, 01:06 AM
Yup, measure the seat tube. Distance from center of BB to the top of the seat tube.

Trek6500ZX
07-19-03, 01:08 AM
Thanks Jim. I am a little slow with some things so I needed to clarify, lol.

bac
07-19-03, 07:07 AM
What about bikes with standard vs. compact geometry?

It seems that similar sized bikes would have very differing frame sizes?

Maelstrom
07-19-03, 10:59 AM
Bac,

Thats when you start seeing terms like virtual top tub and virtual seatstay height. You would have to understand what the degrees are when readin up on the geometry. With the real toptube length, virtual top tube length, seat stay height and then various angles.

tFUnK
07-20-03, 01:11 AM
Originally posted by Maelstrom
Bac,

Thats when you start seeing terms like virtual top tub and virtual seatstay height. You would have to understand what the degrees are when readin up on the geometry. With the real toptube length, virtual top tube length, seat stay height and then various angles.

maelstrom,

i never quite understood the difference between "effective top tube" and "top tube" lengths. effective top tube just means a horizontal measurement, correct? seeing how most frames today have a sloping top tube.

Maelstrom
07-20-03, 01:13 AM
Basically take the measurement from the centre of the headtube and run parellel to the ground to your seattube...that will tell you your effective toptube length and is a better measurement of cockpit size.