Originally Posted by
Steve Whitlatch
I am not sure if that rear derailleur is the kind that uses a smaller #3 or #4 wrench or not but I have run into a few that look like they take a big #6 wrench from the outside. Check to see if the rear of the bolt is turning when you are trying to take it out. If not, you need a smaller wrench.
Aha! Looks like you're right. After shining a light in there I can see that it actually takes a much smaller wrench than it would have you believe. Unfortunately, it looks like it's made to fit a #3 but is stripped and I just can't quite get it to catch. The recess of it makes it a little awkward for home remedies. Perhaps ill just have to weld a wrench to it, or find a way to tap a flathead into it.