What length do i need, is it as simple as getting one the same length as the post in there now??

Almost… Check how much of your post is out of the frame and how much is in and take it from there… I think min insertion is 80mm. And about 225mm min seat post clamp to rail clamps… But dont quote me on that last figure!

they now do a 4″ model as opposed to the 5″ and correct about 80mm.

I did wonder wether your comment was going to start ‘before it breaks’

the answer to that is of course ‘imminent’

Just buy the longest one and cut it down? 😀

I have the 380mm model with 125mm drop. Unless your seat post extends a very long way out of your seat tube you should be fine with that.

About 5 seconds?

I have a 350mm post at the mo on my Zesty.. I do have quite a lot of post showing because of my long legs. But its obviously not past the min insertion thing.. So was thinking 380mm.

I just went for the longest, there wasn’t (hardly) any weight in it.

190mm is the minimum exposed seatpost from top of the seatpost clamp to the saddle rails. If you require 210mm of exposed seatpost and 100mm minimum within the frame then you need the 380mm version.
If you needed 300mm of exposed seatpost with 100mm minimum within the frame then you need the 440mm version as the 380mm wouldn’t leave you enough exposed seatpost or not enough within the frame.

Cheers Craig.. I’ll get busy with the tape measure.