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Looking at dropper posts and trying to work out what overall length to get
My current fixed post length is 300mm, post showing 150mm and total insert available into frame is 200mm
I was thinking that a 380mm one would work with a 125mm drop however that would mean that the post will never be at fully extended - is this an issue?
Or should I go for a smaller length one?
Height 5'9"
Cheers
Kwack
Fixed post length is 300mm
You've got 150mm showing and 200 in the frame?
150+200=350mm
??
This might help..
[img] 
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I had the same thought once my first ne was delivered, fortunately it was fine.
I would suggest that you go for the shorter drop post so you can set the fully extended position perfect for climbing. It will be a total faff to have the fully extended length too high for you. You are paying all that money for convenience so it should be set up so its super easy and quick to set the height where you want it.
Ooh, never seen that chart. Perfect.
You really want it so that fully extended is at your ideal pedalling height. Doesn't really matter if fully in is too low - it's more controllable anyway, or use the enduro collar that comes with them now.
Can't remember where I got this from so can't credit, but I saved this when I was shopping for one. It's an issue if you have a restricted seat tube - use measurements from your current post to get the longest one that will work for you at full height and still be within the minimum insertion.
[i]380mm post / 125mm Travel:
Distance from centre of saddle rail to base of collar at Fully Extended Position (aprox) * = 188mm
Distance from base of collar to bottom of seatpost (aprox) * = 187mm
Minimum Seatpost Insertion: 80mm
420mm post / 125mm Travel:
Distance from centre of saddle rail to base of collar at Fully Extended Position (aprox) * = 188mm
Distance from base of collar to bottom of seatpost (aprox) * = 227mm
Minimum Seatpost Insertion: 80mm
355mm post / 100mm Travel:
Distance from centre of saddle rail to base of collar at Fully Extended Position (aprox) * = 163mm
Distance from base of collar to bottom of seatpost (aprox) * = 187mm
Minimum Seatpost Insertion: 80mm
420mm post / 100mm Travel:
Distance from centre of saddle rail to base of collar at Fully Extended Position (aprox) * = 163mm
Distance from base of collar to bottom of seatpost (aprox) * = 252mm
Minimum Seatpost Insertion: 80mm[/i]
Thanks that does help.
The maximum insertion is around 200mm into the frame - specialised enduro
I currently have 150mm inserted.
I guess it depends on whether you should ride a dropper post fully extended or not at all?
Looks like a small one at 355mm would suit - just the one that Merlin doesnt have
It will mean if you press return when standing or off the bike the saddle will be too high for you.
if this happens when riding it could lead to you having a painful accident!
So just remeasured and I got the figures all wrong
Current seat post length 345
Post above collar 195
Post below collar 150
Maximum available insert 200
So after all that I reckon a 380mm post will fit
I think where I went wrong was I was not including the whole bit that connects to the seat itself