I've been having problems with my 3-speed Curve for some time now. The gears don't shift smoothly, and I sometimes can barely access first gear.
For a while I thought it was simply tension on the shifter cable near the hub. I would experiment getting the tension just right, and sometimes it works for a while.
I also had problems with gears seeming to slip from time to time, usually when going uphill and there's I'm pressing harder on the pedals. It would tend to crop up when I had recently done work on the rear wheel - changing tires, usually. It's difficult to get the rear wheel in just the right position.
Now, I suspect neither of these may be the cause. I've gotten the tension on the shifter cable and on the chain correct, I think, and the gears keep almost-slipping and the shifting still doesn't work. Am I making false assumptions here? Anyone see this before?