Yes, spoke protector. I don't know what it called and I was just guessing.
Here's an image of spoke protector loose.
The spoke protector that got loose and somehow it jammed the cassette. If I pedaling it, it runs normal, but when I stopped pedaling (cruising) the chain would go waving and banging on chainstay that got my attention. I stopped and checked it, I noticed that if I backpedal it, the chain would pull rear derailleur and top chain would get "sagged". And then I noticed the spoke protector was loose. It's possible that it broke while I rode (I have run across some rough road).
Originally Posted by
FBinNY
To answer the question as asked, no you don't need one and plenty of us don't have one, but the consequences of RD misadjustment will probably be much more severe without one. It's like doing a high wire act without a net, perfectly safe if you're good enough, a poor decision if you're not.
So, it's like 50/50 chance. Don't the front derailleur would prevent chain from it go over last sprocket?