Originally Posted by
mstateglfr
A cable pull brake lever can be used with mechanical disc brakes. Its quite simple. Tiagra STI will work just fine with cable disc brakes.
As for the claim that an MTB brake caliper is needed, no that isnt the case. Cable brake levers can be used with common cable disc brake calipers like TRP Spyre, Avid BB5, Tektro Aries, etc etc.
The style of caliper mount on your frame(flat mount, post mount, etc) needs to match the disc brake caliper mounts. There are adapters available for some to work together.
Just to be clear....
IF the OP needs Road calipers, then he needs Road calipers, which are no more "common" than MTB calipers. And not only would he not
need MTB calipers, they would actually be the
wrong caliper.
BB5s, BB7s, and Tektro Aries all come in both Road and MTB versions. You have to get the right version of whichever you you go with.
Spyres are all for Road (Spykes are TRP's MTB version of that caliper).