Seat Post/Seat Tube Question

[cloudchaser]

Hi all,

Recently picked up a new to me Serotta. As a bit of bling for my new baby, I want to get an Eriksen Sweetpost. The bike has a 30.9 seattube, but currently has a shim and is running a 27.2 seatpost. The sweetpost is offered in both 30.9 and 27.2 sizes.

Any advantage running one size over the other?

I haven't tried to remove the shim, should it slip right out, or might it be cemented in there by galvanic corrosion if not properly prepped?

I am leaning toward the 27.2 for greater compatibility with other frame sets and the ease of install, but wanted to see if I was overlooking anything.

Thanks in advance.

[dave thompson]

Hi all,

Recently picked up a new to me Serotta. As a bit of bling for my new baby, I want to get an Eriksen Sweetpost. The bike has a 30.9 seattube, but currently has a shim and is running a 27.2 seatpost. The sweetpost is offered in both 30.9 and 27.2 sizes.

Any advantage running one size over the other?

I haven't tried to remove the shim, should it slip right out, or might it be cemented in there by galvanic corrosion if not properly prepped?

I am leaning toward the 27.2 for greater compatibility with other frame sets and the ease of install, but wanted to see if I was overlooking anything.

Thanks in advance.
One of my Serottas had the same 30.9 seat tube with a 27.2 shim. I used the shim and purchased another 27.2 seat post as they are ubiquitous and offer the most variety. And if you ever decide to sell a 27.2 seat post, it's attractive to many more folks.

I greased the shim, inside and out. so it wouldn't become stuck in the frame.

[Brian Smith]

I think that regarding the seatpost size, I would recommend the 30.9 for those most concerned with achieving a lack of creaking or slipping, and for those who are likely to often move the seatpost in and out of the frame. For those who prioritize interchangeability of posts among frames, or who want the greatest selection of posts, perhaps the 27.2 and shim is a better option.

For my own use, I would opt for simplicity and the shim-less 30.9, but then I do have probably 15 or more 27.2 posts within 100 yards of my workstands.

[bicycletricycle]

shims are for when you cannot get the proper sized part.

[cloudchaser]

Thanks for the input, will go with the 30.9.