Seven Redsky seatpost size question

[DavidMtl]

I Just bought a used Seven Redsky.

The seatpost (not a Seven) is 30.9mm with a shim. Without the use of a shim it would needs a 31.6mm seatpost.

I am wondering if the frame was intended to have that setup (30.9mm with a shim) since, on their website, Seven offer their home brand seatpost in either 27.2mm or 30.9mm only.

I need to change the seatpost to have one with more setback so I'm wondering what size to look for 30.9mm or 31.6mm.

The 100mm long shim make it look not to bad so if there is no disadvantage to it I may continu using it with a 30.9mm.

Any thoughts about that?

Thanks a lot!

[Pegoready]

That's really weird.

Seven's do not ship with, or were intended to run, removable seatpost shims like you have. That frame you have was modified in some way.

Seven's always have glued-in seatpost inserts that are supposed to be permanent. Most (especially on drop bar bikes) use a carbon 27.2 mm insert. 30.9 mm aluminum inserts are bonded in on special request, or on MTB's.

I'd be surprised if the ID on the raw tube is perfectly 31.6 mm. It probably isn't. If you're intent on that plan, I'd try a cheap 31.6 mm seatpost before committing.

I have a feeling someone drilled out or sweated out the original bonded-in shim for unknown reasons. I'd personally have it sent back to Seven to have the proper 27.2 mm shim bonded in. Failing that, I'd keep using the shim and a 30.9 mm seatpost. I don't think a 31.6 is going to fit perfectly in the frame.

[wc1934]

I can't provide much help.
This is what my 2017 redsky spec sheet says:
Seat Post Thompson Black, Aluminum $ - 27.2 mm, 16mm set back, black - RHQ to provide.

[litcrazy]

I know seven isn’t able to provide specs ahead of used purchases but I wonder if you politely and delicately ask, you could procure the original spec sheets at a reasonable cost. No need to ship it back if it’s just an unusual spec for special circumstances.
I don’t claim to have any insider knowledge, but it doesn’t seem impossible that they’d spec a larger diameter seatpost in the case of a much heavier rider.
It’s a pretty upright build too, so I can imagine the rationale.
I’d love to hear what you find out as I took a long look at that frame as not quite my geometry.

[onomic]

I have a Seven Axiom SG with mid-reach brakes, so an older iteration of the Redsky and it has the bonded in carbon shim and it takes a 27.2 seatpost. My wife has a Seven Cross bike and it is the same.
Definitely seems strange, I’d be reaching out to Seven if it was me.

[Peter P.]

Get a Cane Creek shim and use whatever seatpost diameter you want.

I have one on my Soulcraft. The shim hides under the clamp and you get a slim O-ring to snugly fit over the seatpost and protect the junction from water infiltration after a film of grease is applied. That's the way Soulcraft did it.

[buddybikes]

Since that frame is so large, guess it was changed spec to support what that rider needed. Whole idea of custom frame maker.........