i might not have been clear , it works on the wheel that is close to locking up . not both at the same time.
if both wheels are locked at 80 mph , i would be amazed , but at some point 1 will have locked up first , therefore the abs would have acted on that wheel . what do you think happens when both wheels are on ice , and both are locked ? the abs will not react cos it thinks you have stopped.
what it can do is switch from front to rear and back again, as each one is modulated by the abs .
some seem to be missing a bit . abs works whilst brake is applied not when they aren't.
my 1150 will work on the rear only , if i leave the front brake alone , i tried it on the way to work today . it works on the circuit being applied.