sabinaq said:
Hi, thanks for responding. The current seatpost is 50.5 cm long up to where the diameter reduces so you can put the seat on
it. 15 cm are below the limit line, ie 15 cm remain inside the tube of the bike when you raise the seatpost to the limit line. It's diameter is 3 cm.
Any advice appreciated.
You didn't indicate how much longer you needed/wanted the seatpost to be ...
The ideal situation will/(would) be if the current seatpost is STEEL ...
What I would probably try to do is to create an intermediate, telescoping seat tube extension ...
Regardless, with the seatpost that you have, see if the INNER DIAMETER is 25.4mm, or larger ... BUT, not much larger
because an alloy seatpost is probably not an ideal structural choice.
If it is, then you can use the existing seatpost as the middle piece ...
You'll need a seatpost collar which will fit over the 30mm (30.9mm? 29.2mm?) seatpost which will become a part of the seat tube ...
AFTER you find a seatpost with a smaller diameter which will sleeve snugly-but-smoothly inside the current seatpost, you would remove the current "cradle" at the top, cut a 5cm expansion/compression slot in the end ... clean the cut edges with a file ...
Insert the original "seatpost" into the frame ...
Install the collar, lube the
new seatpost and insert it into the extension, adjust ... VOILA!
FYI. The longest (that I know of) 25.4mm seatpost is 350mm long ... 270mm usable length from the minimum extension line to the cradle.
After subtracting the lost length from truncating your current seatpost, you could add between 8-to-9 inches (20-to-23 cm). If you need MORE than that, then you probably have to get a different folding bike which has a larger frame (e.g., the type that use 26" wheels, or larger).
Presuming you need less than 20 cm more length, leave more of the intermediate section inserted in the frame than not ... and, I would want to have more than the minimum insertion of the seatpost in the extension, too; so, hopefully, you only need about 15 cm more extension.
