CWC seatpost shim/collar

[SkyknightJohn]

Gathering parts for a 1950 CWC...
The seat tube has this slotted insert/shim that fits a 5/8” post. The tube without the insert is 13/16”. I can find a 13/16” layback post easy-cheesy that will fit a modern type seat.

Is this removable? or is it welded/brazed in place? It only goes 2-3” down the tube.

Would it be simpler to find or fabricate a 5/8” post?

Thanks.

 

[B + M]

I have a 1941 cwc frame I'm working on and that insert has a weld bead around the top holding it in. I don't know if that's stock or someone before me welded it up.

This may not answer your questions but here was what I did.

I bought a two foot long piece of 2024 solid aluminum rod from McMaster Carr for less than $10 and a Hillman zinc spacer ( 5/8" x 7/8" x 1 1/2") from Lowes, the spacer fit on the aluminum rod with a little help from a hammer. The spacer fits perfect in newer seat guts and the aluminum fit perfect in the frame. I've gotten a few rides on it and it seams pretty strong. I would imagine with the right tools you could bend it for a layback post.

 

[SkyknightJohn]

Cool. Thanks. I’ll have to pull the seat collar off to see if there’s a weld bead on below those tabs. I’ll try to fab a tool to pull the insert out as well, without damaging the seat tube, and after the build off starts.

 

[RustyGold]

You can only bend 2024 aluminum slightly without seriously weakening it...unless you plan to anneal it before bending and re-heat treating after. Otherwise, it will crack and eventually fail (sooner rather than later).

3000 or 5000 series are better for bending, but..aren't heat treatable and therefore not quite as strong.

Jason

 

[SkyknightJohn]

I tinkered a bit today, the clamp came off fine. The insert and the seat tube seem separate enough, but the insert was disinclined to budge. In the meantime, I have a modern sized steel seat post that will fit fine over the 5/8” rod. Might be the easiest solution.