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Discussion Starter · #1 ·
thinking about getting a new ride so i am comparing geometry from my x-5 which i like to some 29er bikes... i couldn't figure out why the geo spec on ventana's web site for TT didn't match the measurement i was getting...then i saw the blueprint on the ventana site that showed they measure their top tubes from the center of the head tube (horizontally) to the rear of the seat tube... i was measuring center to center.... which i thought was how most manuf measure... does anyone know if ventana is the only one measuring this way or am i way off and do all manuf measure this way and not center to center... ex..the 21" x-5 measures 24.5" center to center and 24.9" center of head set to rear of seat tube....thanks for the info !!
 

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Discussion Starter · #2 ·
i did get the TT measurement

from the ventana site like you suggested but the only way i can come up with the same measurement as the site is by measuring center of the head tube to the rear edge of the seat tube (not the center of the seat tube)... the picture on the site seems to show the TT measurement as going to the edge of the seat tube also.... maybe i'll call sherwood to clarify... thanks for the reply..
 

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Warton,

the little picture is just a representation. The length given in the B column is in fact the "Effective Top Tube" length which the industry has somewhat adopted as the norm.

Effective top tube lengths are measured from the center of the headtube to center of the projected seat tube, (effectively your seatpost) when measured on a horizontal plane (parallel to the ground) from the top of the head tube.
 

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Discussion Starter · #4 ·
Tt

thats the way i thought they were measured but i keep coming up short.... i keep getting around 24.5 or 24.6 for a top tube thats supposed to be 24.9.....not that a half inch makes that much of a difference anyway.... i was just wondering if the industry uses the same standard... center of head tube to center of projected seat tube (horizontal) like you said....
 

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warton said:
thats the way i thought they were measured but i keep coming up short.... i keep getting around 24.5 or 24.6 for a top tube thats supposed to be 24.9.....not that a half inch makes that much of a difference anyway.... i was just wondering if the industry uses the same standard... center of head tube to center of projected seat tube (horizontal) like you said....
MOST companies use the effective top tube standard.
Some use actual top tube. Consult with mfg/geo stats for clarification.

And yeah, .5" on TT makes a big difference - really, the size of a bike is usually only 1" TT difference between S/M and M/L
 
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