I don't remember your username so I'm just putting this out there.
Last week I tightened my disk brakes, specifically at the cables. They had gotten to the point I had to pull the levers all the way to the handlebars and were still feeling weak.
After a little adjusting (I made the front one a little too tight at first) they started feeling great, but this morning on the way to work they started feeling really weak again, like they were barely engaging. Only this time, the levers don't go all the way to the handlebars, the travel distance is the same as when they were doing fine, so it's not that the cable has slipped.
I don't want to over-speculate since I haven't really done this sort of thing before, but I'd appreciate advice on things to check. My workplace has a ton of tools I can borrow if need be.
Definitely sounds more like a mechanical issue if it's the amount of travel that is changing. Kinda silly question, but is the bolt that clamps down on the brake cable on the caliper side tight enough / have the washer in the correct orientation? It sounds like you adjusted them correctly, then the cable slipped a bit causing you to get more play in the system.
I tightened it down a lot, so I doubt it. To be clear, the lever's travel distance hasn't changed, it still could move the same distance (to about 2 finger width) as when it worked fine, but the brake isn't fully engaging. My understanding is that cable slip would have caused the levers to depress all the way back to the handlebar again, or at least a lot closer.
Ah totally! I must have misread your comment.