[Duffimo]

Hello,

I am looking to make a custom oval tube out of carbon to be used as a seatpost for a road bicycle.

The oval tube needs to be 26 mm wide (side-to-side) and 33 mm wide front to back. The lenghts is about 400 mm.

The saddle clamping system will be bought as spare parts for a traditional 31,6 mm in diameter seatpost.

I have the old seatpost which is about 200 mm long that can be used as a template.

What would be the best way to make such a part?

 

[Artemus147]

I am looking to make a custom oval tube out of carbon to be used as a seatpost for a road bicycle. What would be the best way to make such a part?

You are going to use a true oval shaped tube, not one of the truncated ovals that you have pictured?

And how exactly are you planning to install that saddle mounting hardware to it?

 

[Drew Diller]

You are going to use a true oval shaped tube, not one of the truncated ovals that you have pictured?

And how exactly are you planning to install that saddle mounting hardware to it?

I have the same questions as Artemus147.

Since you're talking about a straight profile along a linear path, you can use rubber internal tooling - "platinum cure" (referring to the catalyst, not a marketing shtick) silicone rubber. If you use it at room temperature with liquid resin, it does a decent job at simply displacing a volume where resin will not go. If you make a high temperature mold and use prepreg, the rubber will expand to provide compression. All while avoiding adhesion to epoxy. Silicone only really sticks to ... other silicone. Speaking generally. The silicones that stick to other things are harder to obtain, and are harder to use.

Word of caution on the heat expansion rubber -- it takes some experimentation.

If you don't want to use the rubber method then you have to use an inflation bladder, or something else to displace resin internally and compact the carbon layers just enough.

But seriously -- just a straight oval shape? Why?