No practical way to make a frame smaller (if the post is inserted as far as it will go). When you are seated on the bike, does your leg have a slight bend in it with your foot at the bottom of the pedal stroke? If you rock side to side when pedaling, the bike is absolutely too big.
Try to relax when practicing.
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Bacchetta Giro A20, RANS V-Rex, RANS Screamer