bexley

So, I need to get another 2cm or so out of my seatpost. 3cm would be perfect.

I weigh just 140lb and I'm not off-roading or anything, so how much distance past the min. insertion mark can I get away with?

The placement of this line seems to vary based on a seatpost's length, with longer ones having a higher line. This is a short seatpost (about 14cm from the line to the rails), so the line is already pretty low and I'm not sure how much I should push it.

To put it another way, what's the absolute minimum amount of seatpost that should be in the seattube?

mattface 

Manufacturers tend to be cautious and over engineer. 2cm past the min would probably be fine, but I like to be conservative as well. you should be able to find a slightly longer post no problem. what diameter is it?

markjenn

Well said. There is a safety margin, but it's there for a reason. If you can get a longer post, I'd spend the small amount of money and keep your margin.

- Mark

curiousincident

you might run the theoretical risk of breaking your seat cluster off, but friends of mine have pushed it by as much as 1.5" with no problems. if you want to run it like that for more than just temporarily i'd eventually want to get a longer post.

bexley

26.8

I already got a cheapo MTB post as a stand-in since I thought this one was lost in the mail--then it arrived two days after.

So, I'm not so crazy for the idea of buying a 3rd seatpost for this bike, although eventually I want to find a chrome-line post since mine is rather dull aluminum.

EivlEvo

spend $20? or take one to the kids?

Seems logical?

bexley

I think the better way to ask the question was "how much seatpost should be in the seattube?"

The long-ass Kalloy post has the line 10cm from the bottom, and the Sugino has it just ~6cm from the bottom.

With an extra 2-3cm, that would leave just 2-3cm of the post inside the seattube--dangerous?

bexley

I spent $45 on this post and $25 on the Kalloy, so I'd really like to avoid buying yet another one. $100 total for ending up with a basic post? Shudder.

But I get the message. Once the frustration of overspending on this build passes, I will likely shell out for a new post.

no name

Get a cheap slightly longer aluminum one and polish it up. Won't be as bling as a chrome, but close.
Might be able to work out a trade or something with your short one at your LBS.

*new*guy

i'd be more worried about ovalizing the seat tube or other possible damage to the frame w/ that little post inserted.

sfcrossrider

So would most frame builders. The guy who built my frame (25 years of experience and thousands of frames) told me to make sure the seat post drops below the tt. Maybe he is just cautious, or maybe he's just smart.

bexley

But for the post to drop below the TT only takes ~4cm on a frame without an extended seattube.

To summarize: for short-ish seatposts, is there an approx. agreed-upon length of post that should be inside the ST? Is that "seatpost below the tt"
suggestion a common or safe one?


Edit: Yea, I'm considering stripping the black paint off the Kalloy post, since it comes off so easily, and then polishing. I've already gone through 3 t-shirts polishing parts for this bike, so again....this is not an option I'm looking forward to.

bexley

Oh, and to hopefully put an end to all the suggestions that I'm a cheap ass, this is temporary. I just don't know how long it'll take before I find a nice seatpost in 26.8 at a LBS. I'm f'ing done with having the cost of small parts doubled by inflated shipping from US shops.