Disc brake callipers

murrayp7
murrayp7 Posts: 18
edited August 2017 in Road buying advice
My Cannondale caad optimo came stocked with Promax callipers (post mount with 160 rotor front, flat mount with 140 rotor rear). They're okay-ish, braking has improved since I swapped out the pads and discs (swapped out the wheels for ones which can fit center lock rotors), but in the future I may look at upgrading to better callipers (reduce weight and improve braking power, apparently dual piston systems are better). I'm probably not going to bother (since I'll eventually upgrade to a higher spec bike anyway) but I'd like to know out of interest. The Trp spyre callipers seem to have good reviews, i'd appreciate if someone could recommend some good mechanical disc brakes, but the main question I have is this:

The callipers are advertised as being for 160 or 140, I assume this is not because of the calliper itself but because of the disc that's included with the rotor? As in, the calliper itself does not differ, only the adaptor / disc rotor? I ask this because most callipers on the market (at least on wiggle and chain reaction) are post mount callipers, and as mentioned above I have post mount 160 front and flat mount 140 rear, so the rear differs entirely to the calliper advertised. So if I were to buy said calliper, I would assume I'd have no problem for the front brake, but for the rear if I were to get a post to flat mount adaptor which would I need, the 140 or the 160 adaptor? I would assume 140 if the size of the calliper does not differ but I was hoping someone could clear this up. Because otherwise it is not possible to have both a post to flat adaptor and a separate 160 to 140 adaptor on at the same time (at least to my knowledge). Thanks.