'Nother one of those bike-y weirdness things that only matters to me.
Rear derailleurs typically "relax" to the smallest cog - that little one on the outside you use when you're pedalling as fast as possible. It's your hardest gear, which means many riders don't use it much. If your rear derailleur cable breaks, you're suddenly in the hardest gear to pedal, and you're stuck there.
Decades ago, Shimano made a "Rapid Rise" derailleur that "relaxed" to the biggest cog. The theory was that, on a mountain bike (which is what they were made for), you'd want to get into your easier gears quickly as the terrain changed, and this reversing of the derailleur direction would facilitate that.
Well, like Biopace chainrings, it was one of those "good" ideas that just didn't catch on, and that was that. You just couldn't get them.
Then, the retrogrouches at Rivendell Bikes decided to try to have them made. It took years to find a supplier who would make the small quantity they thought they would sell, and in the meantime there's been a pandemic, tariffs, and who knows what-all else. But they finally brought 'em to market.
I'm always up for some bicycle weirdness. I've been following the progress of the project, and, when Rivendell started an email list to keep prospective customers posted, I put three or four of my email addresses on it. They offered presale in the fall; I credit-carded my way in. They finally sent 'em out a few weeks ago.
I teach the Basic Bicycle Maintenance class at Princeton Adult School, and I use my bikes as teaching aids, so I didn't want to put it on until I'd finished using my bike as a prop. But that day has come (the last class is all students bringing their bikes in for review), so I popped it on today.
It will theoretically index nine speeds (that is, if your shifter snaps from one gear to the next, this derailleur is compatible with a nine-speed system, at a time when eleven speeds are common, twelve speeds are not rare, and thirteen-speed systems are available). But it's really meant for friction shifting, where you slide from one gear to the next. My titanium bike has this system.
Here's running the chain through, after doing the tiny bit of adjustment that it needed,
I took it out for a few miles this morning. I really like it. Rivendell touts that now you pull the cable the same way, both front and rear, to get to the harder gears, and relax it to get to the easier ones. The way I remember it is that I have to pull against resistance to get t a harder gear, both front and back, and ease the lever back in to get to an easier gear, which feels more intuitive to me (although it took some riding to change my default shifting behaviour, after years of having the levers on the bar ends).
It will manage up to a 34-tooth cog in the back (which is large, making for a nice, easy gear for climbing). It takes fewer degrees of level turn to shift than I'm used to, which will take some adjustment. But I like it.
As I write this, they're sold out. Weird bike-y retrogrouches are apparently coming out for 'em.