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How much seatpost to leave in the seat tube?

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How much seatpost to leave in the seat tube?

Old 10-12-06, 09:15 PM
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How much seatpost to leave in the seat tube?

My rough calculations (before I have the parts actually in hand) say I'm gonna have 6-7 inches of seatpost hidden in the seat tube after I get my seat height dialed in. How much of that can I spare cutting off? It's a 50cm frame with a 350mm carbon seatpost. I'm thinking I should leave 4-5 inches? Is more needed because it's carbon?

This question is mostly for sh*ts and giggles....just felt like getting my weightweenie on.

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Old 10-12-06, 09:18 PM
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2ish inches o' post is the minimum, I hear.
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Old 10-12-06, 09:30 PM
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Clear everything of the

1) seat lug/chain stays.

At the least.
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Old 10-12-06, 10:51 PM
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ask the seatpost manufacturer or read the manual. Some posts say 2 inches, others like mine say one third of the seatpost and others just have a mark...

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Old 10-12-06, 11:00 PM
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Originally Posted by Dial_tone
My rough calculations (before I have the parts actually in hand) say I'm gonna have 6-7 inches of seatpost hidden in the seat tube after I get my seat height dialed in. How much of that can I spare cutting off? It's a 50cm frame with a 350mm carbon seatpost. I'm thinking I should leave 4-5 inches? Is more needed because it's carbon?

This question is mostly for sh*ts and giggles....just felt like getting my weightweenie on.
there isn't anything like bracing inside, right?

so measure from the bottom up to the min insertion mark...

But I wouldn't cut a CF seatpost.
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Old 10-12-06, 11:01 PM
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Here's what Easton says:

Insert the seat post into the seat tube.Do not use a rotating motion. Scratches on the seat post can cause stress concentrations that could result in seat post failure.• The seat post must be inserted into the seat tube a MINIMUM of 70 mm (2.75 inches) for proper post life. However, many frames require more than the minimum 70 mm insertion. The seat post must be inserted deep enough into the frame to ensure that the bottom of the seat post extends past the bottom edge of the top tube. Failure to insert the seat post far enough into the frame could result in seat post failure.
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Old 10-13-06, 12:46 AM
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Originally Posted by blandin
Here's what Easton says:

Insert the seat post into the seat tube.Do not use a rotating motion. Scratches on the seat post can cause stress concentrations that could result in seat post failure.• The seat post must be inserted into the seat tube a MINIMUM of 70 mm (2.75 inches) for proper post life. However, many frames require more than the minimum 70 mm insertion. The seat post must be inserted deep enough into the frame to ensure that the bottom of the seat post extends past the bottom edge of the top tube. Failure to insert the seat post far enough into the frame could result in seat post failure.
Below the top tube and a bit more is what I have always used. Not on CF but if you have a metal seat tube and have it above the top tube- The sideways strain on the Post could break the frame at the top tube. The seat post does add rigidity to the frame at this area.
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Old 10-14-06, 03:14 PM
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I ordered a 350mm but the framemaker (Flyte) only recommends 300mm.That's gonna be almost 14 inches of seatpost. I will probalby only have 5 inches exposed so if I leave 4-5 inches in the tube that still leave 4-5 inches of unwanted weight.
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