Reader “Comekk” just sent over photos of his Ultegra Di2 rear derailleur hack. Standard units are only available with short cages, as expressed directly from Shimano:
“Existing Shimano Ultegra Di2 and Dura-Ace 7970 Di2 accommodate cassette gear ranges up to 28T (with SS cages) as well as new Dura-Ace 9070 Di2. That is factory spec as recommended by Shimano.
However there are some aftermarket vendors who have created RD cage solutions on their own to widen the gear range and riders have been tinkering with cages from those vendors and even Shimano to widen the gear range. Again, those options are not ‘formally recommended’ by Shimano with existing Di2 systems and the forthcoming Dura-Ace 9070 system.”
So, what’s a guy to do if he wants more gearing?
Comekk simply took the long cage from a standard mechanical Ultegra derailleur and swapped it in, replacing the Di2’s shorter cage. The only adjustment needed was fiddling with the B-screw tension (and, likely, adding a few chain links).
Simple, and far less expensive than the K-Edge units…which could open this up to more mountain bike hacks by simply getting creative with the climber’s button pods.