Join Date: Apr 2005
Location: SW Washington State
All calipers/brake pads will make contact with the rotor regardless of whether the brake is applied or not, bike, car, truck whatever. So this constant contact results in some heat. Also rotating the rear tire may not spin very far due to the drag of the chain also preventing the tire from free wheeling.
So some of this is normal but if it seems to be excessive heat or friction, pulling the caliper retaining bolts and cleaning the rubber seals around the caliper, these have folds that can retain dirt and prevent complete retraction.
Applying a small amount of grease to the pins that loctate the pads can prevent a dragging pad. The grease goes ONLY on the pins, not the rotor, the caliper or the pads. It is not uncommon for a pad to bind slightly on its pins and become cocked resulting in a dragging pad. Some people will even slightly bevel the edges of the pads pin holes to further prevent this possibility.
Hope this helps.