Folksnake

Hi All
I have a Marin hybrid and I want to change the seatpost to one with a little setback (just looking for a little more room). My calipers tell me that my current post is 27mm; the seatpost I have in mind is available at 26.8 or 27.2. Should I get the 26.8 and shim it up to 27, or get the 27.2 and (carefully!) sand it down to 27? What would you do?

This may be a moot point--I can't seem to find a shim to go from 26.8 to 27--is there such an animal, or is it too small an amount? I suppose I could fabricate my own...

Thanks!

Grand Bois

Sand a 27.2. You only have to remove one tenth of a millimeter. That won't take long.

HillRider

Try the 27.2 before you sand it. Seatposts and seat tubes vary slightly and their tolerances aren't extremely good. Also, does your current seatpost have the diameter stamped on it? Most do near the bottom of the post and below the "minimum insertion" line.

oldroads

Avoid shims if you can.

Folksnake

Thanks for all the good answers--I was guessing that might be the way to go (sanding). Hillrider, I haven't checked mine for markings--should have, but the thought eluded me. Plus, I had my incredibly accurate luthier's calipers, and I get so little chance to use them!

I'll order the 27.2 and see how it fits--might luck out. Otherwise, removing a little shaft material won't be much trouble.

Thanks again, everyone!

Retro Grouch 

The first thing that I would do would be to completely remove my existing seatpost and examine it to find the size that's stamped near the bottom. I'm betting there's a better-than-average chance that will solve your problem.

If you buy a real seatpost shim to match your frame and seatpost it'll have a little flange on the top and you won't have any trouble at all making it work. To fit a 27.0mm frame, however, you'll probably have to start with a 25.4mm seatpost. I don't think that the shims come in 0.1mm thickness.

2372ighost

My Marin hybrid is 27.2

Folksnake

Interesting! Mine's a San Rafael from 2000. I'll check what the post says when I get home....

The one fitted on it now is a suspension Post Moderne.

poopncow

beverage can is just shy of .1 mm in thickness

Folksnake

I just checked; it's 27.0, just as my calipers said. Nice to know that they're perfect!

HillRider

Actually, I'm surprised too. Your calipers are probably much more accurate that the marked size on most seatposts.

Luthier? Do you make instruments or just have the tools?

Folksnake

I don't make a lot of musical instruments, but I have at times, and I do repairs and mods on stuff I have. Guitars, mostly. Another great hobby that comes with great tools! Sometimes I wonder if I pursue interests just to get some of the attendant tools....

Your name is apt, Hillrider--I know a little about the Pittsburgh area, since my mom's from around there (Sewickley, to be exact). My thighs hurt just thinking about that terrain--I mean, isn't that what inclines are for?

Folksnake

Got the new seatpost and installed it this AM. Looks great--it almost fit without sanding; but a minute or two later it fit perfectly (really only had to take off the black powdercoat).

Thanks for your help--