We had a setback with Michele riding a couple of weeks ago - we did an 18 mile round trip to go see Pandas 3D IMAX (it. is. amazing.), and she ended up in a lot of pain on the return trip, but today we did CicLAvia out in Pomona and she did almost 14 miles completely pain free.
I have a theory that part of it comes from stopping and starting - for some reason she doesn't like to get off the saddle, so she tries to put a foot down while staying clipped in with the other foot and on the saddle, which leads to a weird hip shift. We're going to try to keep testing that theory by doing a few rides of increasing distance on things like dedicated bike paths where you rarely have to stop.
Still, another positive step (and another fun CicLAvia).