Bondage bypasses the scenic route to subspace for me. It is a straight path from the first slip of the rope around my body to starting to feel 'floaty'.

I read a Dominant's explanation of this recently. This Dom is Someone I respect a lot and is very experienced.

He wrote that bondage; restraints, rope, leather or cuffs, puts pressure on the limbs.
This pressure is percieved by the brain and endorphines gets dispatched. The tighter and the longer the bondage, the more lovely hormones gets released.

This also happens when kneeling.
No surpise that I love kneeling also.

Being restrained also works with my mind... I always say bondage 'ties up' my mind also. It focusses me on my Dominant.

All good things