We all know the deal with left hand averages vs right hand averages for those that can throw with both hands.  Pick a hand and stay with it.

Question came up in league last week and I didn’t have a clue.    For no thumpers if they choose to bowl two handed are they restricted to bowling only two handed or can they switch back to thumb in one arm bowling?   Can no thumbers/ two handlers allowed to shoot spares with a thumb in ball or one handed.  What are the average requirements.

A two-hander can switch back to one-handed, thumb-in anytime they wish as long as they don't change their dominant hand.  For example, a righty two-hander can switch back and forth to one-handed as long as they use their right hand when bowling one-handed.

As SVstar 34 said, they can only do this in sanctioned competition if they have the compliant equipment.  When throwing no-thumb, their ball cannot have a thumb hole.  They would need to then switch to a ball with a thumb hole and use the hole, if going one-handed with a thumb.