I’d been having problems with my rear derailleur recently. Ultimately, it was sticking on, generally on one side, and it seemed that the entire brake calliper was moving too, essentially moving to the side so that it was stuck on the side of my wheel. It was worse when it was wet, which at the moment is pretty much every day, considering we’ve apparently just had the wettest December in history.
So I figured, after repeatedly trying to tighten the bolt to keep it from moving to the side, and giving it a good clean to make sure it wasn’t gunked up with crap, that the cable was the problem. I put this down to the fact that when I disconnected the cable, the calliper moved back to the fully open position with no problems; so in other words, I’d close it with my hand, and it would spring open. But when I had the cable attached to it, it wouldn’t open fully, and instead it would stay slightly closed, such that it would not free itself from the rim of my wheel.
Therefore, the cable, outer and inner, got changed on Tuesday, after yet another cycle to and from work with a brake effectively on all the time, or alternatively only using my front brake so that the rear brake stayed fully open merely by me not using it. Neither option is good. I changed the cable, and you know what? It made no difference.
This confused me. Why would it open with no problem when the cable was not attached to it, but when I attach a brand new cable to the thing it doesn’t improve? I was pretty much running out of ideas, so I decided to give the spring inside the calliper a spray with the trusty GT85, giving it a good pounding to work the spring and get as much of the GT85 into it as possible, and gave it a good rinse off. That did the job.
This surprised me mainly because the calliper is only about 3 months old, and it’s a Tiagra brake, so it’s not like it is low quality crap. However, there was already some rust starting to appear on the calliper spring, and I suppose it doesn’t take a lot of rain before the rust will start to set in, so some GT85 loosened it up.
The brakes, front and back, are now nicely tightened for tomorrow’s commute.