rcd

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!

DaveSSS 

Inside are threads and a spring. You have to hold on to one end and turn the other end.

rcd

Thanks, Dave. Can’t see anything like a spring — maybe that’s gone missing. Still though, how does simply rotating the housing around the cable ever engage the mechanism so that it, too, will turn? It looks like rotating the plastic housing would just spin it via the ferrules, as I don’t see what would hold part of its innards stationary while rotating another part. Anyone know of any diagrams/pics/videos that might illustrate this?

DaveSSS 

There should be a larger diameter part that has internal threads, so it works like a nut. The smaller diameter part has external threads, so it's like a bolt, with a small through hole for the cable to go through. If the small diameter end is turned CCW, it unscrews and increases tension.

If there are not two diameters, it's not a cable adjuster. Does the frame have an adjuster?

Also see YouTube there are many videos.

shelbyfv

You mentioned a "lever." Maybe what you have is a QR to facilitate wheel removal, w/o an adjuster function.

dedhed

Can you post a picture?

rcd

Sorry, I was just referring to the brake lever, some distance away from this in-line barrel adjuster. I wanted the reader to understand which end of the plastic housing held the metal cup. I’ll try to post a pic tomorrow, but it is simply a very common adjuster enabling you to do small adjustments on the brake (to compensate for pad wear) while riding. I say “very common adjuster” but I suppose the biking world has changed some since I got this bike 20 years ago! Maybe I should have provided a Seniors Alert! 😀

Wilfred Laurier

So is the adjuster part of the brake lever or is it a separate adjuster?

The in-line adjusters are basically a hollow bolt with a cable stop on one end, and a nut with a cable stop on the other end. The cable housing is split and the ends are seated in the cable stops on the 'bolt' and on the 'nut', and turning the 'nut' in relation to the 'bolt' makes the split in the cable housing wider or narrower. Pulling the two ends further apart has the effect of 'tightening' the cable, turning so the two ends are closer together 'loosens' the cable.

rumrunn6

fwiw - when I changed my rear derailer cable I wound up removing the two barrel adjusters cuz I unscrewed one & it flew off the bike. Don’t know how all three of the little parts landed together on the floor next to me. That was a close call. But a good opportunity to clean & lube them. here's what they look like

Doug64

Check this out; it might help. I have them on a T800, T2 and use them on my CX bike.