Does anyone know what size seatpost a 1980/81 Fuji Sports 12 would take? It's a low-end frame made from "Fuji High-Tension Steel Tubing 661," according to the seat-tube sticker. A 25.4 is too small, and a 26.6 is too big. A rough measurement with a slide caliper suggests that it might be 26.0, but that's little better than a guess.

For me, unfortunately, the best way I have found to uncover the size seat post needed is to have several different sizes and see which fit the best...I have tried to use calipers, but with varying results (and, in one of my former careers, I used to measure plastic parts for a living!)...

You do not have to have absolutely every size...just a good selection...and then make educated guesses "in between" the sizes that you have...

Yes, it would help if I had more "in-betweens"--25.4 and 26.6 are pretty far apart.

No idea on post size. Here's what I use for sizing seatposts. Works perfectly.

I am very surprised it isn't 26.8, the near universal standard of Fujis and most Japanese bikes of that era.

Not saying I am right, just that I am very surprised.

Ben

Is it possible the top of the seat post is pinched in slightly keeping the 26.6 from fitting?

I know 26.8 was fairly common but my three Fujis, a NOS '82 Monterey frameset, an '83 Espree and an '86 Team Fuji, are all 26.6. It bums me out because I have a real nice NOS 26.4 fluted seat post I had hoped to use in the '82 or '83.

Yes, that is quite a bit of "educated guessing!"

Wonderful tool...ordered one!

Yes, that looks like a good tool at a reasonable price. I've always wanted to order a set of the Stein seatpost measuring rods, which are machined from aluminum and arguably classier but cost something like $70 for a set of two. I probably would have bitten the bullet before now if they were sold separately, since all I need is the smaller of the two--I can't see myself ever owning a bike with a seatpost bigger than 27.2, which is where I think the small rod ends.

I guess I'll try to make it to the local bike co-op with the frame when they're open on Friday evening and see if they have something that fits. This has been almost completely a parts-bin build so far, so I guess it won't kill me to spend a few bucks for a used seatpost.

I had hoped that the post from a Fuji Special Road Racer [S-10-S] that I have on hand would fit. I think it's 26.8, but it's clearly much too big.

The ears for the seatpost bolt aren't pinched in at all.

I found this tool on eBay for $9.99...if you are interested, I just searched for "Seat Post Measuring Tool" and got the cheaper price...with free shipping in the US...

I know I got mine off ebay and from a US seller for around that price, maybe a bit more.