Folding Bikes - tricks for overextending seatpost?

My seatpost is too short, but I don't want to buy a new one just to have my bike stolen at some point in the future.

So are there any tricks for safely overextending a seatpost? Shims, wood dowels, etc?

My seatpost is too short, but I don't want to buy a new one just to have my bike stolen at some point in the future.

So are there any tricks for safely overextending a seatpost? Shims, wood dowels, etc?

As far as I know, no one has proven the "safely" part of your question.

Seasame Crunch extended his seatpost with a dowel.

I chopped my seatpost and stuck a smaller diameter seatpost in it.

Yes the best way is to make a telescoping setup. It will damage the frame if the ride with a seatpost beyond the maximum extension line - the lever force on the short section of post inside a frame is too large for the frame to bear and it will surely crack.

Depending on how much extra length you need, you might consider a Butt Buddy (http://www.sidetrak.com/Catalog/components.html). It adds about 2", and you get a little extra comfort too. Not as much damping as a Thudbuster, but definitely adequate for on road.

Yes the best way is to make a telescoping setup. It will damage the frame if the ride with a seatpost beyond the maximum extension line - the lever force on the short section of post inside a frame is too large for the frame to bear and it will surely crack.

But if safety recommendations are based on a torque that can be sustained by the seat tube, and someone now effectively exceeds this torque by having a longer seat post than the mfctr at the min insertion, then the means of extending this also is a problem? What is the basis for the mfctrs safety rating (ie, 250 lbs on this bike - one must assume min insertion point @ 250lbs) ?

But if safety recommendations are based on a torque that can be sustained by the seat tube, and someone now effectively exceeds this torque by having a longer seat post than the mfctr at the min insertion, then the means of extending this also is a problem? What is the basis for the mfctrs safety rating (ie, 250 lbs on this bike - one must assume min insertion point @ 250lbs) ?That's true, so if you do make a telescoping setup, it is wise to put the post a fair bit deeper than the maximum extension line. :beer:

I think my folding bike (not dahon) was intended for kids, so it was a bit short for me, 170cm.
based on dahon's telescope seatpost extender, I copied the idea.
I 'circumcised' the original 28.6 seatpost, and put inside it, a 25.4 seatpost, and finished it with a seatclamp.
but the innerside of the 28.6 had to be ground a bit, because there is the "seam", a strip of steel protruding alongside the pipe...

That's true, so if you do make a telescoping setup, it is wise to put the post a fair bit deeper than the maximum extension line. :beer:

That is right. With the Telescoping seatpost, you have PUH-Lenty of extension to do this unless you are a true giant.

I wasn't sure that I really grasped the connection to your bike being stolen...

I wasn't sure that I really grasped the connection to your bike being stolen...

If I spend Y dollars extra on a bike that originally cost X dollars then if/when it gets stolen I've lost X+Y dollars instead of just X dollars.

If I spend Y dollars extra on a bike that originally cost X dollars then if/when it gets stolen I've lost X+Y dollars instead of just X dollars.

You actually expect it to be stolen, yet you're worried about seatpost length? You don't see the inconsistencies in that logic?