Bicycle Mechanics - seat post installation troubles

I took my bike which is a Bianchi Oclet to the bike shop to get a new seat post (my current one is too short). So they measured it to be at 27.2. So i got a Ritchey post.
when i got home, I put the new post on the saddle and then greased up the post. I also put some grease i the seat tube. For some reason the post won't fit. Its supposedly the right size, but it takes a lot of effort just to get it close to the min insertion point. I was reading in some bike manuel that you shouldn't force it so i've kinda given up.
my old seat post practically slides all the way in with just gravity pushing it in (or pulling). My new post is lightly powder coated (or so it appears) whereas my old post is smooth (no paint at all). Maybe that makes the difference. Would it be a good idea to get a smaller size post? I am not sure what i should do short of just taking at back to the bike shop and getting either a smaller post or just have them try to install it. any ideas?

They? With callipers? Do a site search from Bianchi on the model, they have the size.
Was the removed post 272? stamped?

They? With callipers? Do a site search from Bianchi on the model, they have the size.
Was the removed post 272? stamped?


Yeah, the guy in the bike shop used callipers. He really didn't want to measure, because he was sure that it was going to be 27.2, but he did it to please his boss. My other post was stamped, i think. but the ingraving has been rubbed off, but all i can read is "ERT"... probably "INSERT". I checked the bianchi site, but i didn't see anything about my bike (probably too old, its a 94' Oclet).

my mountain bike and road bike are both 27.2 but on my road bike the fit it a little looser than on my mountain bike. chances are your bike is supposed to accept a 27.2 but maybe a little smaller so it takes a bunch of effort to actually get it in....i hope this makes sense

my mountain bike and road bike are both 27.2 but on my road bike the fit it a little looser than on my mountain bike. chances are your bike is supposed to accept a 27.2 but maybe a little smaller so it takes a bunch of effort to actually get it in....i hope this makes sense

Well it turns out that they measured the seatpost wrong and they gave me a seatpost that was too big. My size is actually 26.8 instead of 27.2. So i returned the post and went to another shop. and got one that ended up being to small, so the mech put the shim in, and it works great.