Originally Posted by rccardr

but Shimano actually marketed 5600/6600 STI's as suitable for doubles or triples for at least a year. Bought a bunch of them over time and set them up on doubles per the instructions where the small and big rings were treated as the small and middle rings on a triple, leaving a 'vacant' unused option locked out by the limiting screw on the FD. After awhile -even though the writing on the box didn't change- I started seeing a little tag affixed to each STI indicating that the STI would break if 'overupshifted' beyond the big ring and the warranty would not cover damage caused by doing so. NBD, I thought- they could also be set up for a double by treating the rings the same as the big and middle on a triple, that way the only thing a rider could do was 'overdownshift' and put more slack in the cable.