What’s inside an in-line barrel adjuster?
Tried to post a far more detailed post yesterday, but somehow failed. I have an in-line barrel adjuster on the rear brake of my 20 year old Cannondale T800 touring bike. Turning it either way does nothing, so I’ve disconnected things enough that I can see into the black plastic housing (about 5-6 cm long). On the lever end, there is a metal cup extending from the lip of the housing down inside the housing by about a cm, and a hole in the bottom of the cup allows the cable to pass through. It is more difficult to see down inside the plastic housing from the other end — there MIGHT be a threaded metal piece that enables the lengthening/shortening of the cable (increasing/decreasing tension on the cable). I really can’t see well enough to say, but that would make sense, given how more visible barrel adjusters work.
Maybe some piece has been lost? Maybe something is just seized up? But even if everything were functioning fine, I don’t understand how merely rotating the housing would do ANYTHING to alter the length of the mechanism itself. Turning the plastic housing only appears the rotate the whole unit around the cable, not to turn the adjusting mechanism itself. Yes, I’m going to go buy a replacement, but I’m still curious about what’s happening with the one I have. Enlightenment would be most welcome!