Hi,
I bought a inexpensive bike to comute to work with. I am rather tall (6.6) and I think the bike I bought is just not large enough. I am comfortable except for the seat not being high enough. I went to my LBS that they sold me a seat post that was a bit higher and they told me it was the highest that they carry. Sorry I do not have the measurements handly.

Anyway, do you know any place where I can get extra long seat posts, are there any pitfalls I need to be aware of and is there any danger of having them too long? I have seen some folding bikes with what look like 2 ft long seat posts so I am thinking that might be a good route to take.

Thanks for your help

Lower back pain unless you raise your bars too.

^^^+1^^^
You can get seat posts in most diameters up to 350mm long. Find out what diameter your post is (usually marked on the post below the minimum insertion line) and Google "seat post ??.?" (replace the ??.? with your seat post diameter) and also check on eBay. Depending on diameter, you might get one even longer. As noted above, you probably won't be comfortable unless you raise your bars and, after that, you'll probably find the reach too short to be really comfortable. Bottom line, there is reason bikes are sold in a lot of different sizes.

As alluded to above, be sure not to raise your seatpost up so high that the minimum insertion line is visible! That marks the minimum amount of tube that needs to be inside the frame to provide the mechanical support for the seat and you. The line is often a set of stamped markings such as ">>>>>>>>>>>>>>>>>>> <<<<<<<<<<<<<<<<" around the tube.

Seatposts of 400mm, and more, can be ordered through any shop. Kalloy makes a 400 and Thomson makes a 410, as a couple of examples.

if you are a bit of a bouncy rider-- I am not willing to raise the post above cheaper man. specs--- you must spread the stress -- so to speak--- posts break and lousy stems snap.

???
I'm also looking for a longer seatpost than what I now have.
The standard Dahon folding bike (Speed 7) has a seatpost measuring 580mm. (I have one.)
The Neo Volt Sport electric folding bike also has a seatpost measuring 580mm. (I have one.)
Not sure why the belief that 400mm or so is the longest. Longer for a typical folding bike would be over 580mm.

I bought a Chromoly 1" seatpost under the Red Line Brand. long strong and modestly priced ..

frame larger seat tube bore ? sizing shims make up the difference..

I'm also looking and it's 2014!
For anyone else who comes across this: a good idea is to ensure strength--you don't want to have the post buckle under you. One solution is to find a wooden dowel the right diameter (you'll have to do some planing or power sanding to get the curves out, and taper the top end so it goes in farther) and pound it up into the post. To be sure it doesn't fall out, drill a small hole through the post and into the dowel and insert a long, thin screw or nail

This doesn't add a lot of weight and it's well worth it for the safety factor. This has enabled me to raise the post above the max and still be OK. But I'd rather find a longer post.

Really?! Are you sure it's not 2008?

Seriously though, a quick look on Amazon.com: Online Shopping for Electronics, Apparel, Computers, Books, DVDs & more finds extra long alum seatpost in the $10 range that are plenty strong.

No, it's helped you convince yourself that you're ok. The minimum seat post insertion is also related to frame construction. What can happen is that instead of the seatpost failing, the frame fails because the seatpost isn't inserted far enough.

it is difficult though
to use amazon to buy the op a seatpost
in 2008
unless they also sell time machines

A potential problem with raising the post above the max is damage to the frame as there will be increased leverage working against a shorter insertion area in the frame.

Apparently it also convinced my bike, since I have ridden about 25 miles a week for several years, half of those miles with the additional load and stress (including oscillation every time a bump is encountered) of a 10' surfboard on a Carver rack suspended from the seat post and no deformation or cracks including the frame. The power of suggestion is indeed strong.

Could be, but so what? Snotty remarks solve nothing. I came across this thread this year, and so did you. So guess what: the thread is still relevant. Even though your remarks aren't.

Grow up or tune out.

Apparently it also convinced my bike, since I have ridden about 25 miles a week for several years, half of those miles with the additional load and stress (including oscillation every time a bump is encountered) of a 10' surfboard on a Carver rack suspended from the seat post and no deformation or cracks including the frame. The power of suggestion is indeed strong.

Good point, and I wouldn't do this if I were going to indulge in off-road riding. But on decent city streets it has worked out well for me. I have ridden about 25 miles a week for several years, half of those miles with the additional load and stress (including oscillation every time a bump is encountered) of a 10' surfboard on a Carver rack suspended from the seat post and no deformation or cracks including the frame. The bike is a Dahon Speed 7.

Indeed. And then you risk ruining the frame like this:



https://www.bikeforums.net/framebuild...placement.html

Wilfred; Apparently they do sell time machines... < ROFLOL>

Amazon.com: Big Bang Theory [HD]: Season 1, Episode 14 "The Nerdvana Annihilation [HD]": Amazon Instant Video

Apologies for having fun at your expense...

/K

A typical folding bike post is also much larger in diameter than a typical DF post.Good luck finding a 27.2 post in 580mm.

Right. But neither the OP nor I ever mentioned 27.2. So I won't be needing either the "good luck" to find what I'm not looking for, nor the sarcasm.

The issue of frame damage is certainly real. But there are other factors.

Which is worse: having a post that is, say 1-2 inches longer than standard spec, or a bike at standard spec ridden by someone who weighs 220 pounds, or ridden by someone who hits a lot of large bumps/holes and does not use the legs as shock absorbers?

I leave it to someone else to work out the precise math, but using a bike only on paved surfaces (as I do), avoiding bumps as much as possible (which I do), standing on the pedals to remove weight from the seat if a bump is encountered (which I do), and being of a reasonable body weight (which I am) results in less stress on the post and the bike than someone who uses a normal post at normal height and does none of the above.