Finally made a full trip this Saturday and was quite challenging, but in unexpected ways. On the positive side, the Delta QR block (towed single bike frame with just a wheel in back) performed flawlessly for 25 miles to the co op. The BIG problem came in that the wheel QR loosened itself twice during the trip. First time was about half way in the trip and had the trailing bike rocking significantly side to side. A nice rider "gorillaed" the rear wheel QR and everything seemed fine. But the tightening only made it about 10 more miles. Had to tighten again. Was close to the co op so made it without incidence. At no time, thankfully, did the trailing bike threaten to dismount.

So, the mystery that I hope any of you physics people can solve: Why did the tightened, and then strongly tightened, QR work its way loose? Again, this was just an mtb frame with a properly fitting (indeed the wheel I'd been riding on it as a full bike for 100's of miles) wheel and ride tightened QR. A customer at the co op (engineering student) opined that it may be because there was NO weight on the bike and all the bouncing force was concentrated to loosen the QR. Just doesn't seem right, but what do I know? Hopefully someone with experience and knowledge can chime in.

My take away, for now: attach safety lines to any towed bike AND check that it is at least tracking true without wobbles.

As for turns: all ordinary turning was fine. Once in the co op parking lot I intentionally did the sharpest turn (manually) with the trailer and the trailing bike did, eventually, fall over on its side. But, for the whole 25 miles of shake, rattle and roll, the trailing bike tracked upright.