Cable routing
 

Hello,

I'm turning an old '87 Bianchi Grizzly into a road type bike. Switching the brakes to dual pivot. Front brake is no problem. The rear has a little small issue. The cable. Any ideas on how I can route the cable? It originally came with a U Brake mounted under the chain stay. This is also where the cable bosses are and there are none on the top tube.

Thank you for any advice.

Something like these?

Loose Screws 1 1/8
Loose Screws 1 1/4

I think these are stops but you could buy 2 and run a bare cable along the top tube and housing at either end

That might just work.