RapidRise derailers for open-minded newbies
When you have lever-shifters (downtube, bar-end, thumbies), you move the left one forward to get the low front gear, and you move the right one back, the opposite, to get the low gear. You’ve gotten used to it, because that’s what people do.
A RapidRise derailer flips the opposite wackiness of a normal derailer. In derailer-engineer parlance, most rear derailers are "high-normal," meaning when you relax the cable, the spring pulls them to the high gear. Rapid-Rise is Shimano's trademark name for "low-normal" derailers, in which a relaxed spring pulls them to the low/easy gear.
When your rear derailer is RR/low-normal, you move both levers the same direction for the same result. Yes, it's the opposite of your habit, but it is mechanically intuitive, so you learn fast.
Low-normal derailers have been around since the 1950s, but never caught on. If Campagnolo had made its derailers this way, the shifting world would be different now. Shimano knows it's smarter. When it was more engineering-driven than market/sales driven, it tried hard to reintroduce it from about 1997 to 2004, but bike shops and big manufacturers were too chicken to support it. Shimano must have thought the naysayers were insane. Bike people thought Shimano was.
I don’t have RapidRise on all my bikes, because I have some perfectly good high-normals, and I can go back and forth. But I have it on half, and I MUCH prefer it. Everybody I know who gives it a shot prefers it. Will prefers it. The friends I ride with prefer it. Normal derailers are easy to get used to; RR derailers are easier to love. We have far more normal derailers, and a limited supply of RR ones. We will not provide you emotional support or assurance if you're on the fence. The Nexave derailers we have are NOS (new old stock, never been used, made in 2003 or so), and WE DON'T HAVE MANY, so I shouldn't even be touting them. I'm torn between treating you individually and cheerleading the Nexave, and treating you-all as a group and hoping most of you don't want to walk the weirdo, low-normal path to doom or delight.
They’re larger than other derailers, they look a little weird, but I can't imagine any friction-shifter not preferring them. We don't sell them separately, and when they're gone they're gone.