hi im awaiting delivery of my 456 frame and just had a thought. how long does the seat post need to be into the frame to safely clear the bottom of the toptube ? it looks like it may be a fair depth (and the post if just got from merlin may be too short boo hoo)

needs to reach 1cm below where the bottom of the top tube meets the seat tube (as for pretty much all bikes)

ah but how far is this on a 456 😉 cheers

just that top bit looks long on the frame pix

It is reasonably long (like Konas). At a very rough, from memory estimate, I reckon that the seat tube goes about 4cm above the top tube with the top tube being about 4cm diameter. So that would mean that you need at least 9cm of seatpost in the frame. I stress again, that that’s a very rough guestimate… 😯

cheers i thought it looked like a bit bit but only got worried when my 350mm post arrived today with only 275 mm avail to actually use ;-(

Then again

Looks much longer above the TT than 4cm…

Seat tube is 28.6 diameter so I’d now guess that there are about four seat tube diameters from the top of the seat tube to approx 1cm below the TT so that’s around 11cm

booger lol im waiting for on one to reply but nowt yet cheers mate

My RF seatpost is 330mm approx. and the max marker is at approx 260mm and I have no problems on my On-One 456 Summer. I bought a smaller frame aswell for chucking around riding, so you would presume I’d need a longer seatpost for XC, but at my comfortable set height I have an inch left to the max marker and the end of the seatpost is at the bottom of the top tube, so 1cm short of that which clubber recommends. I would wait and see before you make any assumptions.

BTW my inside leg is 32″ and frame size is a 16″.

It needs to be something like at least 1cm below the lowest point of the seattube/toptube weld; I think that Brant mentioned that this should be find. If you’re a big bloke like me you might want a bit more just to be sure (I’ve got a long post which puts a bit of extra in the seattube on my 853 and DN6 Inbreds). If you’ve got a shimmed post then I think that the shim itself needs to meet the minimum insertion requirements.

B.A.Nana, the min. insertion mark on the seatpost has nothing to do with the min. insertion point for a frame. It’s there to show the minimum amount of post that has to be in the frame to protect the post from snapping. The min. insertion point for a frame is to protect the seat tube from snapping. Even if you meet the minimum insertion requirement for for post you still ought to check that you meet the min. insert requirement for the frame; it’s usally a point below the lowest part of the seattube/toptube weld (so for extended seattubes it can be quite a bit).

so do you know how long it is from clearing the bottom of the top tube to the top of the seat tube ? as if its 10cm then i need a new post for sure. cheers

Ok cheers, didn’t know that.

I don’t know off the top of my head I’m afraid. I’ve got a 20″ 853 Inbred at home, assuming your 456 is 20″ and that the geometry is the same I could measure mine when I get home.

It sounds like it’s going to be tight and if it is 1cm below the bottom of the weld that’s going to be a minimum. The was a discussion about this on the On-One forums but I don’t think they exist anymore.

mines a 16 mate. with the amount of post i need out i could only really put about 7cm into the frame with my 350mm post (i stupidly just thought a 350mm post would have 350mm of usable length and the bit inside , how silly of me lol)

I always use a 400mm post, no worries then,.

100mm is 10mm past bottom of top tube

looks like you need a new post

merci mate ;-( at least i can return this one to merlin unused

Thats on a 16″ summer season BTW just measured it

mine is normal but im presuming its the same. cheers fella