Oversized seat tube choice

Education
1

Hello all !

I’m having some troubles choosing a seat tube for taller guy. 1,9m.
I’d like to go with external butted seat tube and no weird sized post.

I,m tempted to go with ZON113635 seat tube but the 0.9mm wall thickness makes me inconfortable as I’m used to the common 1.2 external butted seat tubes wich I think is good.
Is this tube intended to be used with a shim and 27.2 seat post ?

What are the choices to go with standard posts and “oversized” seat tubes ?

I like the idea of using a collar but I don’t feel confortable enough to TIG this atm. I believe I’ll practice and try this later. For now I focus on fillet wich I enjoy a lot especially raw.

Kiss

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“I like the idea of using a collar but I don’t feel confortable enough to TIG this”

This is why framebuilders who TIG should also be able to braze. And to a degree why so many TIGed frames have removeable seat collars. Andy

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Reynolds has some nice long and fatter walled seattubes, for instance CX2474: 853 34.1/34.9 X1.15/.55/.8 X650 - BB
Or the 631 variant: CX5474: 631 34.1/34.9 X1.15/.55/.8 X650 BB

And I have been using the Columbus ZON113600002 a lot lately, but they just dissapeared from the biketubing.com webshop, so dont know whats going there…

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Reynolds got some with 650 length for 27.2 seatposts:
853
CX2364 — 853 29.8/28.6 X 1.2/.6/.9 BB X 650
631
CX5364 — 631 29.8/28.6 X 1.2/.6/.9 BB X 650

CX means “Seat tube”
OD X Wall thicknesses X Length
BB: Bulge butted

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Do you mean the CX5287? It’s 30.9mm ID, externally butted, and has a wall of 1.1mm at the top. That’s what I would use in the OP’s situation.

But I think Columbus must reckon 0.9 at the top is OK for a TIG frame with a large ST. I have used ZONI113550001 on TIG frames and they were fine.

6

I use 1 3/8" (35mm) .063" straight gauge from aircraft spruce for my extra heavy duty seat tubes. It fits a 31.6 seat post perfectly.

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Hello all !
Thanks for your help !
I’ll go with reynolds CX5474 as advised @project12 or keep with columbus ZON113640.
Wich would you choose for 90kg 191 cm rider ? Comuter, light travel, rare gravel, drop bar bike.

@AndrewRStewart I did not get it.

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8

I think @Andrew was thinking about seatclamps. You were talking about a weld-in insert to the top of the seattube to reduce the ID.

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Hi !
I did used CX5474 and it was nice.
Now on next design I’d like to go for a 31.7 seat tube with aluminium shim.
Did someone used the ZON113635 from columbus or TV317B304 from dedacciai ?
Does it hold with 0.9mm thickness ?
Is it possible to not ream after welding since there is the aluminium sleeve ?

Thank you.
Kiss

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Interesting question. Seat collars - should you TIG weld it on or braze it on? Why?

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What’s your tool? A hammer or a screwdriver? Both attach stuff to other stuff. My tool is is brazing so that’s what I have done for binder collars, and just about all other bits too. Were I starting over again (and young enough to still have space in my brain) I would learn TiG welding, and think about Ti… Andy (still glad I can braze)