sorry guys i found the answer. i post it coz it might be helpful for others.

Greyhound baggage restrictions:

• For
  passengers traveling on Greyhound schedules, one (1) piece of baggage
  will be free for each adult and child. One (1) additional piece of
  baggage can be accepted for a charge of $10.00 for adults only. One (1)
  small bag, up to 25 pounds, plus one personal item (purse, handbag,
  etc) can be taken aboard for each adult or child. Carry one bags must
  fit in the overhead compartment or under the seat.
• Baggage
  must not exceed 158 centimeters (62 inches) when adding the total
  exterior dimensions of the (length + height + width). Any Bags
  exceeding the 158 cm. (62 inch) limit will be assessed oversized
  baggage charges. The only exception to the oversized surcharge is skis
  and ski poles, assuming they are packed in an appropriate canvas or
  hardcover container. Bicycles can be accepted as baggage only if they
  are in a cardboard box designed for bicycles and are subject to the
  maximum oversized baggage charge regardless of the distance traveled.
• The
  "no charge" allowance for baggage is restricted to 23 kilograms (50
  pounds) per bag. Baggage exceeding fifty (50) pounds per bag will be
  subject to overweight baggage charges. Baggage over 32 kilograms (70
  pounds) per bag will not be accepted.