To lock up your high-value electric bike, you want the best protection on the market. There are a few third-party security rating organizations that we trust. 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. If you've got a highly valuable, attractive bike that thieves want, and it's out of your sight for protracted periods in a public place? Look for a bike lock that's ranked Sold Secure Diamond, then bring in other considerations.
Most of the highest-rated locks are U-locks, though these are of course heavy and may require a bracket on your bicycle to carry comfortably. For a regular-size U-lock, you’ll usually want to lock the bike around the frame and the back wheel, if space allows. Some methods suggest simply locking the back wheel, but this can leave the rest of your bike vulnerable. You’ll want to keep U-locks away from the ground, especially with concrete or asphalt, to prevent thieves from trying to smash it with a hammer or using leverage devices like a tire jack or iron.
The components on electric bikes are also valuable, so you'll need to protect them as well. You can thread separate steel cables through your wheels and rack, or alternatively, you can use a secondary lock as we have suggested above. Chain locks can work well for securing both a frame and wheel, though they have their drawbacks. They’re usually quite heavy, especially the thicker ones that can better resist heavy bolt cutters. They’re also generally not nearly as grinder-resistant as our top picks. Again, keeping the chain off the ground will help ward off bolt-cutting thieves.
Of course, the best lock is the lock you'll actually use. If you find it difficult to tote a big, bulky, grinder-resistant lock around? You might want to consider a folding lock, even though those are slightly less secure.