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Seatpost length advice needed please.

662 Views 3 Replies 3 Participants Last post by  TiEndo
Got a Small size 5 spot
When the seat post is raised to achieve a comfortable pedaling position, it is extended 28cm above the top of the seat tube.
In order to decide the length of the seat post I should use, I need to know how deep it should reach into the seat tube.

The yellow line marks the reach of the 350 seat post
The green line marks the reach of the 400 seat post.
The blue line marks the maximum insertion of the seat post :rolleyes:

How deep should it reach into the seat tube?
Why can't it be inserted beyond that certain point?

Thanks in advance


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Saar G7, per Turner website link below, recommended 100mm min insertion, which looks to be near the middle of your green and yellow indicators. Say take the 400 post and trim it 20mm if you are looking to get more drop room and still have the hundo recommended.

Others have found some of the 2009 seat tubes need reaming to get full insertion. Not sure what the outcome was for the new 2010's?
Thanks moosehead

I will ride it like that for a while, I will trim it 10-20 mm only if I have to lower it some more..
Any seatube needs to reach past the toptube junction to prevent leverage force from cracking your frame. Do not use the min insertion line on your post as a judge (that is the posts integrity).

You are probably hitting the taper of the tube or the weld penetration for the linkage. Measure to your ideal position and cut a 400mm to length needed.
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