At 10:05 AM -0400 5/16/08, coel canth wrote:
>were you surprised because you expected the seattube's inner diameter to be
>27.2 ?
>
>to get a good sliding fit between the seatpost & seattube, the ID needs to
>be a bit larger..
>27.4 is the normal size required for using the ubiquitous 27.2 seatpost
And if the 27.2 seatpost slips downward, then try using a 27.4... If that does not fit, you either have to ream the seat tube a tad, or custom-machine a 27.3 mm seatpin.
I once had a bike that needed a top tube replacement. After the top tube was replaced (and presumably the seat tube reamed again to get ride of any distortion), the seatpost size had gone from 27.2 to 27.4 mm... The seat tube was the same, just reamed a little larger.
Jan Heine
Editor
Bicycle Quarterly
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Seattle WA 98122
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