Yet again, I've experimented so you don't have to 
As I have explained before, I would like a rear rack. But I don't want a seatpost mounted rack, because I don't want to have to deal with it when I fold the bike. Hence I wanted to try to do something like the R&M Birdy "expedition" rack that folds with the bike.
I noticed that the
Delta Megarack Sport has a hinge, so thought it would be a good starting point. It's quite light, made of aluminium, and seems sturdy. Not what you need for your next self-supported world tour, but perfectly ok around town and for commuting (I've used it for 3 months on my beater bike, and loaded it very heavily).
As you can see from the pictures, I
mounted it to the pre-drilled & tapped holes over the track slots and to the upper seatpost quick-release. I had to drill out the upper/front rack mounts to allow the quick-release skewer to go through. The rest of the fitting process was very straight forward.
It looks kind of funny on the bike, but readily accepted my Ortlieb. As you see, even with the pannier adjusted as far back as possible I get terminal
heel strike... I wear size 11 or 12 shoes, so if you have smaller feet this might work for you. Actually, the upper mounts have enough adjustment to get the pannier another 2 inches further back, but it makes the top of the rack rather flexy and also made the folded package
even bigger.
Speaking of the
fold, it makes the fold bigger. Between 3" and 5", depending on how far back the front rack mounts are adjusted. (It doesn't stick out past the rear of the seat, but it's 3-5" measured from the seatpost). Not ideal, but if it had been otherwise functional I wouldn't have minded. I don't think those extra 3" would stop me on Caltrain.
Conclusion: well, now I know for sure it doesn't work for me. If your feet are smaller than 11-12 it might be worth considering. I've since discovered that my Ortlieb fits fine on the front, but haven't taken a picture of that yet..
