can this "stiffness" be affected if the rear wheel isnt properly tensioned?

aj

edit: i ride a caad9 with xero lite wheels. it has 20 spokes in the back and im thinking about taking it in to get a complete wheel true.

Frame & wheel are two separate things.
I have one of those wheels ... so flexy the rim hits the brakes when I sprint ...... might be ok for a light rider.