Burg Wachter Sold Secure Gold 14mm Motorbike U Lock

For it’s size you won’t get much better than this! I’ve seen that there quite a few different versions of this lock from Oxford etc, however this is definitely the best one. It’s the only one with a diamond level bicycle rating and the gold motobike rating is plenty enough for me to have confidence in it’s abilities to prevent theft. I reckon you’d be at it with an angle grinder for at least 5 minutes before you got it off completely!