Dear friend,
"Ignorance of law is no excuse " - by signing the bond and joining the services it implies that you accepted the conditions stipulated in the bond by the organization with your eyes and mind open. Just because a better opportunity is on your way now, you can not retract. However, one can not say that an employment bond becomes absolutely enforceable just because the employee simply agreed to all the terms and conditions. It depends on the nature of the terms and conditions. If any such condition in the employment bond is opposed to public policy as per sec.23 of the Indian Contract Act,1872, the bond can not pass legal scrutiny. Therefore, before giving an appropriate answer to your query, it is essential that the terms and conditions of the bond are disclosed by you.