The chainline thing...
If you caliper is mounted within the rear triangle. You can only go from say 1mm from fowling the caliper body to pulling it 6mm directly out. The loss of pad contact area will be loads more.
Sorry to but in...
...do those ^ drop outs mean that you don't have to worry about adjusting your brakes as the caliper moves as you effectively adjust the dropout/chain length?
Sorry to but in...
...do those ^ drop outs mean that you don't have to worry about adjusting your brakes as the caliper moves as you effectively adjust the dropout/chain length?