>>1898348In dry humid climates it's actually not a terrible thing, first that part of the frame is stiffer which improves braking performance, roller cam brakes were thought to be something that would become standard on high performance mtb's, they were so powerful that they were capable of actually flexing the seat stay assembly and causing the brake pads to misalign in relation to the rims resulting in poor contact. Roller cams were fantastic, far superior to any other =rim braking system, except for one fatal flaw, as the pads wore down they worked their way closer to the tyre and would eventually cause blow outs if the pads weren't changed in time.
The only serious drawback to chain stay mounted brakes is mud clogging them up, but in sunny California where these things were dreamed up they'd never heard of mud.
