# Weld in seat collars



## RCP FAB (Jun 15, 2011)

Walt, if this shouldn't be here, let me know.

I am going to have a run of weld in seat collars made. They will be made to use a *30.9*mm seat post into 1.375x.035 (34.9x.9) tubing. They will be 2.5" OAL, .5" of that slips into the tubing.

They will be machined from 17-4 bar stock.

The minimum order to get these at a reasonable price is 50 pieces, that price is good for up to 199 pieces. I am not looking to make any money on these, just to help cover the costs of the minimum. I can comfortably cover 20 of them. Pricing below covers actual cost of parts + shipping to US, + $3 for cc fees/packing materials.

12 will fit in a flat rate box. If we can get it up to 200 pieces, the price will drop about $5 per piece (if it gets close to that I will post here). If you are interested email me ([email protected]), once I have confirmation for at least 30 I will have them made.

Thanks

1 - $27
2 - $45
3 - $63
4 - $81
5 - $99
6 - $117
7 - $135
8 - $153
9 - $171
10 - $189
11 - $207
12 - $225


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## pvd (Jan 4, 2006)

30.9 is a more common size. Any chance of getting some of those done?


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## Walt (Jan 23, 2004)

*Just FYI*

1 3/8 x .065" is pretty much a perfect slip fit for 31.6 posts. 5 minutes on the lathe and you're good to go. That's a commonly available size in both stainless (304, anyway) and 4130.

-Walt


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## RCP FAB (Jun 15, 2011)

Peter, I can do them 30.9 instead, if that's what people want, or I am sure he will do a mixed batch.

Walt, I have had mixed luck using .065 wall tubing, one stick I ordered worked nice, the other was a little loose.

Plus, 17-4 welds in nice, and you can leave the top half inch unpainted so the seat clamp doesn't mess up the paint.


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## Walt (Jan 23, 2004)

*Weird.*

Did you check the fit before you welded everything up? 4130 can sometimes be out of spec, just like any other tubing. Measure, check, doublecheck!

I think I've done 40 bikes with the 31.6 posts using .065 4130 and I can't recall ever having a loose one - in fact I've always had to ream them post-weld.

-Walt



RCP FAB said:


> Peter, I can do them 30.9 instead, if that's what people want, or I am sure he will do a mixed batch.
> 
> Walt, I have had mixed luck using .065 wall tubing, one stick I ordered worked nice, the other was a little loose.
> 
> Plus, 17-4 welds in nice, and you can leave the top half inch unpainted so the seat clamp doesn't mess up the paint.


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## RCP FAB (Jun 15, 2011)

Yes, I did check, it was within the mills tolerances also, so my buddy ended up with a 4 foot cheater pipe, its been about a year now and it still hasn't bent.


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## Walt (Jan 23, 2004)

*Huh?*

What is their tolerance? 1 3/8 x .065 is about a 31.62mm ID which has always worked great for me. Even if it was 31.7 or so - once you distort it a little and such you'll need to ream a tad anyway.

If I were you I'd do 30.9. That's a more difficult size to do yourself without lots of lathe time and you'll have better luck selling them to other builders.

-Walt



RCP FAB said:


> Yes, I did check, it was within the mills tolerances also, so my buddy ended up with a 4 foot cheater pipe, its been about a year now and it still hasn't bent.


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## RCP FAB (Jun 15, 2011)

Walt,

I don't recall what the specs were, but the ID was 31.8, it *probably* would have worked, but I didn't want to risk it.

30.9 seems like a good idea, it seems like all of the dropper posts are available in 30.9.

Thanks


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## Walt (Jan 23, 2004)

*That is .058"*

You had the wrong size. That's the ID of .058".

Everything dropper-wise comes in 30.9, *almost* everything comes in 31.6. So I would do 30.9 if I were you.

-Walt



RCP FAB said:


> Walt,
> 
> I don't recall what the specs were, but the ID was 31.8, it *probably* would have worked, but I didn't want to risk it.
> 
> ...


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## RCP FAB (Jun 15, 2011)

Walt said:


> You had the wrong size. That's the ID of .058".
> 
> Everything dropper-wise comes in 30.9, *almost* everything comes in 31.6. So I would do 30.9 if I were you.
> 
> -Walt


Coulda been :thumbsup:

I updated the first post, 30.9mm it is.


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## RCP FAB (Jun 15, 2011)

5 down, 25 to go!


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## RCP FAB (Jun 15, 2011)

Another 2 accounted for. If anyone wants these in 31.6 he said no additional charge to open them up after the batch of 50 are made.


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## Meriwether (Jul 26, 2007)

*Pmw*

Looks like Paragon ended up making 30.9 collars finally! Right on.
MS2019


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## thedudeman (Nov 10, 2006)

On that collar, I'm assuming the post only contacts the collar once its welded to a tube? Does that make for a flexy seat post interface, or do they come out feeling solid?
Looks like a cool idea


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## adarn (Aug 11, 2009)

Good thing I just bought all that straight gauge to make a bunch of these. Oh well. Good thing I just started sharing space in a CNC shop.


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## Meriwether (Jul 26, 2007)

thedudeman- these type of fused-in collars have been standard operating procedure for years on many TIG welded frames with 27.2 posts, especially Ti builders. This was just a new size that covers all the dropper-post sizes, and as said by others, is more difficult/takes more time to fabricate at home (if you have a lathe). 
Adam- now with your new digs...how about a simple and relatively cheap steel yoke for 3" tires?


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## thedudeman (Nov 10, 2006)

Meriwether said:


> thedudeman- these type of fused-in collars have been standard operating procedure for years on many TIG welded frames with 27.2 posts, especially Ti builders. This was just a new size that covers all the dropper-post sizes, and as said by others, is more difficult/takes more time to fabricate at home (if you have a lathe).
> Adam- now with your new digs...how about a simple and relatively cheap steel yoke for 3" tires?


Meriwether- so it must work pretty well then... Are these typically brazed or welded in? 
Thanks!
Scott


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## Meriwether (Jul 26, 2007)

Scott,
They're usually (always?) fused/welded into a tube of the same diameter but smaller wall thickness. Then you weld (or braze I guess) the top tube and seatstays to the collar alone or split the difference to bolster the fused joint.
See photos for example. 1st on is the fused tubes, the 2nd one is the top tube welded 50/50 on the collar and lower set tube. The seastays will be welded to the opposite side of the top tube.


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## shirk (Mar 24, 2004)

Why not just use one of the now available larger diameter butted seat tubes like the TrueTemper VERUSSTMAG?


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## thedudeman (Nov 10, 2006)

Meriwether- thanks for the examples! The weld looks nice flush with the tube like that. I used the verusstmag on the build I'm doing- and it's the heaviest tube on the frame- I'm assuming you could save a bit of weight with this technique?
Scott


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## Walt (Jan 23, 2004)

Why do you want a tube for a 33.1mm seatpost? Or am I misreading the VERUSSTMAG specs somehow? 

The topper allows a lot of flexibility in what you use for the lower portion. If someone was making a seat tube for 31.6 or 30.9 specifically, I still might use the topper just because the extra wall thickness makes for a really nice beefy seatpost interface and also requires minimal reaming. You can use all sorts of different stuff for the lower portion to keep the weight reasonable. 

-Walt


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## thedudeman (Nov 10, 2006)

*VERUSSTMAG typo?*



Walt said:


> Why do you want a tube for a 33.1mm seatpost? Or am I misreading the VERUSSTMAG specs somehow?


I think it may be a typo... 34.9 OD minus the wall thickness (1.6 x 2)=31.7 ID

(maybe it was accidentally calculated for the thin side of the tube 33.3?)

The old .pdf version shows it for 31.6 post, which is what I received, and my 31.6 post fits well (so far).









http://henryjames.com/pdf/HJBpricelist2014.pdf


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## shirk (Mar 24, 2004)

Walt said:


> Why do you want a tube for a 33.1mm seatpost? Or am I misreading the VERUSSTMAG specs somehow?
> 
> The topper allows a lot of flexibility in what you use for the lower portion. If someone was making a seat tube for 31.6 or 30.9 specifically, I still might use the topper just because the extra wall thickness makes for a really nice beefy seatpost interface and also requires minimal reaming. You can use all sorts of different stuff for the lower portion to keep the weight reasonable.
> 
> -Walt


That is a typo, it fits a 31.6 seat post, these are tubes that Chromag had TT draw for use with dropper posts.


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## Meriwether (Jul 26, 2007)

thedudeman said:


> Meriwether- thanks for the examples! The weld looks nice flush with the tube like that. I used the verusstmag on the build I'm doing- and it's the heaviest tube on the frame- I'm assuming you could save a bit of weight with this technique?
> Scott


I'm sorry, just saw this response now...oops.
I use 0.035" wall straight gauge because i mostly do this technique on bent seat tubes and...that's mostly what I bend for seat tubes. So it's not lighter than a triple butted tube at all, or a external butted tube. But you can use most any wall thickness below the collar if you're turning it yourself. Just maket he shelf thicker/thinner depending on desired internal diameter.


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## Fort Colin (Dec 1, 2013)

Hey Meriwether, Thanks for the info! Does that mean that your seat post is only held in by the seat collar so not to the bottom of the top tube junction?

A few years ago a local builder told me that I need to make sure my sleeves go past the bottom of the top tube junction to not have failures caused by the seat post and seems you have a different experience.


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## Meriwether (Jul 26, 2007)

On the ones I make and buy from Paragon have a 1/2" shelf (that is inside the lower part of the seat tube). I've seen many builders, if not most, weld the top tube and seatstays entirely *above* the fused junction of the collar and seat tube (to the thicker collar only). But I learned you should straddle the two so to support that fused junction as seen in the photo above. I don't think it matters but I haven't heard what you have heard. Are you sure it's not failures/cracks in the seat tube when the seat post wasn't inserted below the bottom of the top tube and nothing about the weld-in collar?

But to answer your question... the bottom of the collar's shelf is pretty darn close to coming to the bottom of the top tube.


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## Fort Colin (Dec 1, 2013)

Meriwether said:


> Are you sure it's not failures/cracks in the seat tube when the seat post wasn't inserted below the bottom of the top tube and nothing about the weld-in collar?


You are correct, it was about the seat post needing to be supported. I was thinking that the collar is an extension of the seat post and therefore it might also fail if not fully supported by the TT.

Thanks for clarification!
Colin


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