Hi, I'm looking to overhaul my seatpost on my Bianchi Vigorelli. On Bianchi's website, it says the seatpost is "Bianchi Alloy," except it feels to be carbon fiber to me...it's definitely not a metal of any type - it feels like a plastic (which is why I'm thinking it's carbon fiber).

I just removed the seatpost from the seat tube, and there was a lot of grease/lube, which I removed with a clean rag. I'm about to wash it with some kerosene to degrease it completely. But after that I'm not sure what to do. Is kerosene appropriate to use? Or is there something more appropriate / better to remove grease with?

I'm curious as to what specific kind of grease/lube to use, and where I should apply that. On the inside of the seat tube, and the outside of the seatpost? Etc.

I'm thinking about getting a jar of Phil Waterproof Grease, but it's specifically written that it's for ball and roller bearings? Can I use this on a seatpost?

Also, I'm looking to replace the seatpost (and seat). There is a number on my current seatpost which reads "27.2," but when I measure it I'm getting 270mm. However, the inside diameter of the seat tube is 272mm, which I'm guessing the number of the seatpost is referring to. So when I go to purchase a seatpost, I should purchase a 27.0cm one, correct?

All help is appreciated.

Thanks

Not familiar enough with CF components to give advice there, but...

27.2 is the diameter of the post, so make sure that whatever length you get, you buy a 27.2 diameter.
270mm (27cm) is the length, I'm guessing, so yeah you can replace it with the same length if it's working out fine.

What's the reason for replacing it?

If you go with carbon fiber seatpost, you need to find carbon assembly compound as a lube. There are some pretty SERIOUS guys who will tell you NOT to use grease on a CF seatpost. I know that I had one partially seize up, and after a lot of effort to remove it, some of the surface was peeled off. I had NOT used lube (either type) when I put it in, so it came back to bite me. I am now using alloy posts, and use a Teflon grease to install them, to forestall the drama of another seized post.

Wait! Hahah...the information I provided was inaccurate.

Correction: The seatpost says "27.2" ; when I measure the diameter of the outside seapost, it comes out to be 27.0mm. When I measure the inside diameter of the seat tube, it comes out to be just a bit over 27.0mm (around 27.2 I'm guessing). So I would be best to get a 27mm diameter seatpost, obviously - I think - since that's the diameter of the seatpost I have now. I'm just curious what the "27.2" means that's written on my current seatpost.

And I'm just looking to upgrade a few parts on the bike, since it's completely stock right now. So I'm looking to get a new (better) seatpost and seat as of now.

27.2 is the diameter of the seatpost (that's why 27.2 is imprinted on it) and that is the size that you need. The inner diameter of the seat tube should be the same size as the outer diameter of the seat post.

I thought it was wise to get a seatpost 1-2mm smaller in diameter than the seat tube inner diameter?

no

only if you want the post to slide down every time that you ride

Lol...alright

Any comments about grease?

Dont buy another seatpost until you decide what quality you want to improve - length, weight, set-back, suspension. Same goes for the seat.

Measuring to the 3rd decimal on a vernier caliper is what you need to refer to , as .. if you use a more casual tool it will give you too generalized an answer.. 27.200mm ideally though 27.195 would be close , as would 27.215 , for example
precision tools give you precise answers.

and if its a Carbon post , I'd go with the carbon assembly paste ,
If you are a heavy rider , then I'd look into a quality Aluminum seat-post instead ,
then the normal wipe of grease is adequate.
Re do that regularly to keep post from getting stuck.