seatpost length for compact frame

sam218 said:

Hi, I'm wondering what length seatpost is usually recommended for compact aluminum frames. Is 250mm enough? Is 330mm too long?

250mm too short?-yes.
330mm too long?-no.

sam218 said:

Hi, I'm wondering what length seatpost is usually recommended for compact aluminum frames. Is 250mm enough? Is 330mm too long?

The one that's "recommended" is the one that puts your saddle at the right height 😄 measure your current saddle height from the bb center to the top of your saddle on your current setup. when you measure the seat tube on your new compact frame, subtract that measurement from your old saddle height figure. that tells you how much it'll stick out (plus the saddle!) from the seat tube. then you can tell if a 250 or 330 will do...

oh yeah...if you find the above too complicated....just get the 330 and cut off the portion you don't need if it's too long!

I was riding a Litespeed Capella for a few months and, with the factory seatpost, could not extend it enough to get my seat height correct. I think it was a 300 mm seatpost. Here's where I think you'll find a problem with the compact frames that are a bit small for your size. You'll be feeling a lot of flex on that 30cm of lever force sitting out of the seat tube. I think top of seat tube measured from BB was 47cm. I need 790mm from BB to seat top.

I can't imagine how the mfctrs of both the frame and the seat tube can intend for someone, without knowing their weight, to ride with so much extension when you think of the definition of Torque (F cross l).

sam218 said:

Hi, I'm wondering what length seatpost is usually recommended for compact aluminum frames. Is 250mm enough? Is 330mm too long?

you can always shorten a long one. A too short one makes a poor paperweight.

sam218 said:

Hi, I'm wondering what length seatpost is usually recommended for compact aluminum frames. Is 250mm enough? Is 330mm too long?

Whatever it takes is the answer. 250mm works fine for mine, but it's only a "sloping top tube", maybe not as severe as some compact frames.

How's this for compact???

http://www.cyclingnews.com/photos.php?id=photos/2003/jul03/krefeld/CFkrefeld041

it's not the length of the stick, it's the magic in the wand😉

O.K., now for some usefull advice. If your present seat post, at the correct seat height for you, and doesn't insert into your frame at least 1 inch below the toptube you'll need a longer post. Too short a post will put stresses on the frame at the seatstay/toptube junction and will eventually fatigue and break. That's why there is a minimum insertion line marked on seat posts. Don't cut a seat post just to save weight. That little extra post will help distribute the load on the above mentioned part of the frame.
L.P.Schafer