There are many ways to lock your bike securely, some of which will depend on the type of lock you’re using and the bike you’re locking. Sold Secure, an English security group, issues security ratings for each bike lock based on how hard a thief will have to work to steal your bike. Look for a bike lock that's ranked Sold Secure Diamond, then bring in other considerations. Alternatively, you could use multiple locks, like a grinder-resistant lock for the frame and back wheel plus a chain or cable lock for the front wheel. If you find it difficult to tote a big, bulky, grinder-resistant lock around?