[attachment=3937]Noticed after replacing the rear deraileur that the chain has a kink/bend in the spot shown in the photo. How should I straighten it out?
your best option would be to replace it.
There are two kinds of people in the world, "Those who help themselves to people, and those who help people!"
I agree with PK to replace. It's strength integrity is compromised.
However - if you just Have to ride and no immidiate access to a new chain... See the inner plates in the center of the pic where the twist is?
Take two small pliers and grip them around the outer plates on each side. GENTLY twist it back into shape. You'll compromise the chains strength further as this will probably cause distortion on the pins that hold it all together. Ride like it could snap at Any Time! Very Carefully.
Wheelies don't pop themselves. (from a QBP fortune cookie)