I've gotten used to this setup now and I really love riding it. Most of the time I've just left the bike or trike in it's top gear when using hub motors, except on hills which have always been a problem, both near home and on longer rides elsewhere.
But... got a break in the rain yesterday and took a 24 mile ride. About a mile into the ride 5th gear got noisy and soon just spun out. I figured the Nexus was toast but the other gears seemed to be fine. Then at about mile 15 7th and 8th gears both starting skipping and making noise. Turned out the Nexus had just gotten out of adjustment and with a little research I learned how to properly adjust it and everything seems fine now. Probably didn't help it any to get so far out of adjustment.
But... On my ride to check out the Nexus something started knocking in the motor area. Stopped twice and couldn't find any problems. So today I started out on another ride, and even though everything was running smoothly, the knocking was getting worse, so I returned home. Coming up my hill it sounded like an old Ford with a bad connecting rod. Turned out to be the new Shimano freewheel on the motor. Just 30 miles and it is gone. Actually was still working okay, but has so much slop it flops from side to side under load and the knock was the metal to metal strike as it flopped.
Had read about freewheel problems, but thought it applied to the higher power rigs, plus I am working hard not to over stress the Nexus by starting up in lower gears, always pedaling first, and bringing the motor up to speed slowly. Quick research seems to indicate that the ENO BMX single speed freewheels just fit 1/8" chain and my tripple length chain is 3/32".
I have a 14T track cog and a bottom bracket lock ring that I'm going to try for the time being. Hopefully with a little blue Loktite on the lock ring the cog will stay on. There won't be much pressure trying to unscrew it, but the whole motor will turn when just pedaling, which will be trying to unscrew the cog. The cog teeth are closer to the motor and there's not enough threads to add any spacers, so I'll have to redo other spacers to keep the chain alligned. Should get this tested tomorrow.
This will probablly be just a temporary fix because I like to pedal without the motor and expect the lack of a freewheel on the motor will be noticed, depending on the cogging effect. Going to the EPower Challenge at PIR in Portland this coming weekend, so when I get out to civilization might be able to find a good freewheel at a regular bike shop instead of taking pot luck again on-line.