Minimum...ahem....'insertion length'.....cough....ahem....

LikeClockwork · Aug 6, 2015

Yes I know it's marked on the seat post, but I cut one down by an inch or so kind of 'ish' and now obviously the min. insert marks aren't correct!

I vaguely remember reading somewhere (not Cosmopolitan) that it's 3 inches....?

Also, it's for this bike - viewtopic.php?f=21&t=329290 and I'm worrying that it may need more 'insertion' because of the leverage effect that angle on the seat post will have on the seat tube? Wish I'd never cut it down now :facepalm: I thought I had to or it would start to catch on the bend in the seat tube....

mattr · Aug 6, 2015

Rule of thumb is two inches beyond the bottom of the seat tube cluster. But this varies on the frame design, and who you speak to.

Usually best to trIal fit before you start slicing shit up!

RobMac · Aug 6, 2015

Re:

If you cut off about a inch then redraw a new minimum insertion line a inch 'above' the old one.

mattr · Aug 7, 2015

That's only for the seat pin.
Some frames have their own minimum insertion.......

RobMac · Aug 7, 2015

Re:

I've just measure 28 posts for you and the vast majority are 4" and the rest are 3".
All of which were alloy if that has any bearing.

LikeClockwork · Aug 7, 2015

Re: Re:

RobMac":1mrr2iu8 said:
I've just measure 28 posts for you and the vast majority are 4" and the rest are 3".
All of which were alloy if that has any bearing.

:shock:

Blimey, thanks Rob, were you very bored after that?!!

Ah, well I've marked it at 3", not knowing exactly how much we cut off, and that does seem to take it about an inch above the original insertion limit mark.

I think with this frame, the design would make 4" insertion the max anyway, by then you'd be hitting the point in the seat tube where it starts to bend.

And yes, I was a tw*t, I shouldn't have cut it at all, I was looking at the amount of seat post showing and not allowing for the fact it went back more than it went up, so to speak.... :facepalm:

scant · Aug 7, 2015

mattr":17taxv9s said:
Rule of thumb is two inches beyond the bottom of the seat tube cluster. But this varies on the frame design

agreed

02gf74 · Aug 9, 2015

Most posts ive seen tend to be 100 mm or 4 in, one or two may be less by 10 mm or so. 75 mm/3 in seems a bit short.

RobMac · Aug 9, 2015

Re: Re:

I agree with 02gf74

RobMac":5yl6ln9q said:
I've just measure 28 posts for you and the vast majority are 4"/100mm and the rest are 3"/75mm.
All of which were alloy if that has any bearing.

LikeClockwork · Aug 9, 2015

Re:

Thanks chaps, especially Rob, thanks again for taking the time to measure!

Off out there in a mo to have a proper look and do some more assessing of the situation, have found a cheap and reasonably light post I could replace it with, I'm not going to take any risks. Even though I'm lightweight, a failure in that area could be painful!

Minimum...ahem....'insertion length'.....cough....ahem....

LikeClockwork

mattr

Old School Grand Master

RobMac

mattr

Old School Grand Master

RobMac

LikeClockwork

scant

Retro Wizard

02gf74

Old School Grand Master

RobMac

LikeClockwork

Similar threads

Latest posts