Bicycle Mechanics - Measuring seatpost offset

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Adohrn
05-28-08, 12:53 PM
I like the campy seatpost, but the offset does not work for me. Even with maximum adjustment I'm around 1 cm forward of knee over pedal. I know knee over pedal doesn't mean much, but I generally like setups in that ball park with some tinkering. Currently I'm just falling forward. I figure I need at least another 2cm of offset so I have something to work with. The question I have I how is offset measured so I can shop for a new seatpost.

A new saddle is an option, but since I already own 3 with minimum adjustment a new seatpost would be easier.

Seatpost diameter 26.4
Lenght 200mm

Also any suggestions about which seatpost to buy would be appreciated.

It seems that 26.4 is an odd size. Anyone have any luck with the shims?

Adohrn
05-28-08, 03:17 PM
Found this NOS for $40. Can anyone tell me anything about it.
LWaB
05-28-08, 09:25 PM
You are very unlikely to find a 26.4 mm seatpost that will get you 20 mm further back. Virtually all seatposts with lots of SPO (seat post offset) are 27.2.

merlin55
05-28-08, 09:36 PM
set back is the horizontal distance between the centerline of the seatpost shaft and the center of the 2 rail clamps. 26.4 is indeed an uncommon size now. I have old bike with a 26.8 seatpost....perhaps you could buy a 26.8 and have it turned on a lathe, of course if you had to pay for that it would exceed the cost of the post...
Adohrn
05-28-08, 10:15 PM
Really appreciate the advice. Can't say I was happy to hear it.

The milremo looks like it might give me at least a centimeter of play just because of the way it clamps. Anybody know anything about this brand.

I have also been looking at using a 25.4 seat post and shiming. I have found a few with 20mm setback that might work. Anyone have anything positive or negative to say about shims.

Thanks for any help.