# can a seatpost be too long and cause problems?



## fah35 (Sep 17, 2004)

I found a good deal on a seatpost but its length is 400mm. and it is aluminum. Usually I use a 280 mm or a 350 mm. I can probably shorten it by sawing it. If I put the 400 mm seatpost in a carbon frame will it cause problems ? Since it is in so deep will it affect the frame ?


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## Greg Smalter (Jul 16, 2005)

Unless it fouls on something (like water bottle cage screws), it can't cause a problem. It is possible to cut it, but you should also cross out the Min. insert line when you do that.


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## skyliner1004 (May 9, 2010)

just make sure it inserts past the junction of the top tube on the seat tube line. also you'll need carbon paste.


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## ewitz (Sep 11, 2002)

skyliner1004 said:


> just make sure it inserts past the junction of the top tube on the seat tube line. also you'll need carbon paste.


Why? It's aluminum


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## andulong (Nov 23, 2006)

ewitz said:


> Why? It's aluminum


 Probably 'cause the frame is carbon.


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## cxwrench (Nov 9, 2004)

fah35 said:


> I found a good deal on a seatpost but its length is 400mm. and it is aluminum. Usually I use a 280 mm or a 350 mm. I can probably shorten it by sawing it. If I put the 400 mm seatpost in a carbon frame will it cause problems ? Since it is in so deep will it affect the frame ?


how can anyone possibly answer this question w/o knowing what frame you have and what size it is? 
find your proper seat height, then look at the min insertion mark for the post and measure that...then add it to your seat height line and cut the rest off if you're worried about it. just file the cut smooth before you put it back in your frame.


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## skyliner1004 (May 9, 2010)

whenever u mix carbon and aluminum u want to use carbon paste. if you dont, its your fault if you crash and fall


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## mrcookie (Mar 30, 2008)

never had problems w/ aluminum post in carbon frame w/ regular grease. i've heard it's only a problem w/ carbon-carbon installs ?


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## Brick Tamland (Mar 31, 2006)

Whatever you do, if you have a carbon fiber bike and an aluminum seat post, DO NOT leave your bike in your car on a hot day. The aluminum post will basically super-heat the inside of the frame and melt it. Then, when you take it out, it cools and contracts. Then you head out for a ride and your seat tube explodes at mile 30.

Don't ask me how I know this.


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## skyliner1004 (May 9, 2010)

mrcookie said:


> never had problems w/ aluminum post in carbon frame w/ regular grease. i've heard it's only a problem w/ carbon-carbon installs ?


sure, do your thing


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## been200mph (May 28, 2004)

Does Trek make good seatposts?


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## Derf (Jul 1, 2003)

I remember reading somewhere recently, maybe on velonews tech that a too long seat post can lead to noise in the frame. Please do not quote me, but I remember it.

Can't you cut it, a hacksaw should fly through aluminum and then file the edge round.


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## Derf (Jul 1, 2003)

FOund what I was thinking about...

"Yes, I can. There is only a section of the upper seat tube that fits tightly around the seatpost, and, below that, the tube flares out and has a larger inner diameter. If the seatpost extends much beyond that smaller-ID section, there will be movement of the end of the post inside of the seat tube, and that is what was causing the noise. Remove some length, and the noise goes away.

-Lennard"

http://velonews.competitor.com/2010...aps-seatpost-creaking-mystery-creaking_136734


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