I'd have though with discs you'd want some bigger tubing.
The brake load mostly goes into the chainstay, but what goes into the seat stay is mainly compression. Compare that with a rim brake, which converts brake load almost exclusively into bending load in the middle of a long thin seat stay and you can see that pencil stays are probably more out of place on a rim braked bike than they are on a disc braked bike.
The brake load mostly goes into the chainstay, but what goes into the seat stay is mainly compression. Compare that with a rim brake, which converts brake load almost exclusively into bending load in the middle of a long thin seat stay and you can see that pencil stays are probably more out of place on a rim braked bike than they are on a disc braked bike.