I am working on a friends Blackbird for him after a small wreck. He broke his right rearset, which I replaced. I pumped the rear brake to make sure it moved properly and it was hard as hell to pump. At the same time I had the front wheel off and noticed the middle piston in the calipers had completlely closed the pads. I cannot move the pads apart to save my life. Is there something I am missing here about the linked braking system. The other two pistons were so easy to push back I was able to do it with my hands. Does anybody have any insight on why this is? I would appreciate any help or advice. Thanks!

As you pressed the rear pedal, you activated the middle front pistons.
Did you try to retract the pistons with the pads on (and with the aid of a screwdriver) .
If this is not working, open the center bleed nipple and try again. Don't forget to attach a hose for the brake fluid.

If this still doesn't works, tell us. We'll come up with something.

Oh yeah, I definatlely used pressure to try to get the piston back. I need to try what you said and open the nipple but I wanted to know if there was something I was missing before trying something that might let air in the lines, because it looks like it would be a pain in the ass to bleed the brakes on this bike. I will give that a try tomorrow, but it still seems that it shouldn't have that much resistance. The back wheel is still really hard to turn and the brake lever is fully retracted. Thanks for the help.

Look for the obvious first. Take off the rearset and make sure that the cylinder still isn't compressed because the pedal or something else is jamming it.

It sounds like the rear brake lever or linkage might be bent and not allowing the master cylinder to fully release the pressure in the system. That would explain why you can not push back the pad on the front caliper.
I would check the back end 1st so if that is the problem, you will immediatly know when the pressure is released.
Also-- Is the brake light staying on?- That is another sign of lingering pressure.

Looked at it in a little more detail today and you guys were right. The back of the brake pedal was bent and not allowing the cylinder shaft to move freely. New brake pedal and it will be good as new. Thanks for the help and keep it on two wheels, or at least one!