We got off the ferry in Patmos in the dark and cycled off towards the campground 2 km away. It soon became clear Margo’s derailleur was seriously out of alignment, probably due to the hanger being bent. We had parked the bikes as instructed on the car deck of the ferry, but they were too close to a rack of suitcases, one of which must have fallen into the derailleur.
Margo told me that Kirk, the experienced mechanic at Caps Bicycle Shop, who has done extensive touring, had told her “just bend it back”.
Well it took most of the day to achieve. First we read the Park Tools Manual which we had with us in pdf format. This revealed we had to build a suitable alignment gauge (from junk found around the campsite), so we would know both the direction in which to bend it and when it was back within tolerance. Then we had to find a suitable long lever to use as a pry. Finally, iteratively bending it back and measuring progress took an hour or so.
It was a success and I wish to thank Kirk for his comment. Without it, Margo would probably not have let me take a 2.5 metre long pipe to her bike, and I would probably have given up along the way.
We celebrated by going for a swim at the local beach, which turned out to be topless, quite a contrast to dress codes in Muslim Turkey!