I'm having a problem with the rear dual caliper brake. The brake gets stuck in the closed position when I apply pressure to the lever. The only way I can release the brakes is by physically pulling the brake pads off the rim. I have centered the brake, lubed the joints and tightened the cable to no avail. Any suggestions?
Sounds like one of two things: either there isn't enough spring tension on your brake arms, or your pads have worn to the shape of the rim and are getting stuck. You could try removing and resurfacing the pads and then reinstall them.
If it's not the pads, upload a photo of your brakes so we can help you with the spring tension.
Are these side pull or center pull calipers. Side pull brakes need the correct spacers and you need to be sure the mounting bolt isn't bent. Center pull brakes can get bent and bind to each other. Both need good return springs.
I would suspect one of two things. Either the caliper itself is overtightened or the cable is binding. First check the cable. If you disconnect it from the brake it should slide smoothly and easily through the housing. If not, you may need to replace it, regrease it, or check for sharp bends/breaks. If that's ok, check the caliper. The bolt that the caliper pivots on can be overtightened. It is like an axle cone, it should be loose enough for the brake to move smoothly, but not so loose you get sloppiness or play in the brake arms.