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Old 11-23-11, 12:54 PM   #1
FieldEffect
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Why did Trek make a 36.4mm seat tube?

Most 31.8mm seat posts sit in 34.9mm seat tubes. So why did Trek go with 36.4mm on some of their bikes?
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Old 11-23-11, 03:08 PM   #2
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because they can.....too bad for you
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Old 11-23-11, 03:25 PM   #3
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too bad for you
why is that?
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Old 11-23-11, 03:33 PM   #4
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What did you use to get this measurement?
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Old 11-23-11, 03:47 PM   #5
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What did you use to get this measurement?
The internet
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Old 11-23-11, 04:08 PM   #6
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Are you sure that interior diameter isn't still 31.8 mm? There are quite a few 36.4 mm seatpost clamps available, so apparently seat tubes with a 36.4 mm exterior diameter aren't that uncommon. It could just be a matter of thicker walled tubing.
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Old 11-23-11, 05:12 PM   #7
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Are you sure that interior diameter isn't still 31.8 mm? There are quite a few 36.4 mm seatpost clamps available, so apparently seat tubes with a 36.4 mm exterior diameter aren't that uncommon. It could just be a matter of thicker walled tubing.
It is 31.8. I never said otherwise.
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Old 11-23-11, 05:58 PM   #8
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It is 31.8. I never said otherwise.
Ok, then I don't understand the point of your original question. If you understand that it's just thicker tubing, surely you can think of reasons why Trek might've used it. Increased strength of the tube comes to mind. Perhaps they were having frames with seat tube failures, and were looking to address that? Does it matter that the exterior diameter of the seat tube is larger than on other bikes?
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Old 11-23-11, 07:44 PM   #9
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FWIW
Tubes for bike frames end up being usually imperial , inches, and fraction of such.
metric equivalency numbers get used ..

OD, 7/8", 1", 1.125, 1.25, etc.. wall thickness varies the ID

the C&V folks struggle to find french exclusive sizes. that round down to whole MM.

Last edited by fietsbob; 11-23-11 at 11:33 PM.
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Old 11-23-11, 10:31 PM   #10
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I think you meant 31.6mm, not 31.8mm. Never seen a 31.8 on a Trek (or anything else I can recall... maybe Giant?). Anyway, I think the answer to the main question is that's just how it came out when their engineers were done picking a wall thickness for their tube.
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Old 11-24-11, 07:43 AM   #11
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FWIW, my old Klein also has a 36.4 OD seat tube / seat clamp and uses a 31.6 seat post. Think the 36.4 standard is typical of fat tubed aluminum frames from Trek and Klein.
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