I needed help with this, it was technical and had to be correct. I purchased a brake mount jig from Insepi, read the instructions and gave it a try, double checking all the measurements.
Photo: Insepi brake mount jig in place for rear post mount brake mounts.
I wanted to fit a 203mm brake rotor on the rear wheel and also wanted the brake calliper to be on the chain stay inside the rear triangle for a cleaner loo to the frame. I made a cardboard disc rotor to see if it would fit inside the chain stay and drew diagrams to double check. It would fit. The post mount fixtures would mean cutting the chain stay and then restrengthening I which felt risky but I’d add plenty of extra carbon cloth to compensate. It looked quite brutal after being unwrapped but some gentle sanding soon improved it.
Photo: Post mount barrel nuts glued in place ready for wrapping with wet layup carbon cloth.
Photo: Wet carbon cloth compressed with tightly bound tape.
Photo: Unwrapping the peeler ply, bleeder cloth and tape after the resin has cured.
Photo: Cured joint before being cleaned up.
Photo: Post mount fittings and dropouts after gentle sanding and checking the brake calliper and thru axle fit.
Tavelo Tandems 