Bicycle Mechanics - Extra Long Seat Post

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.