extending a second bolt 5 through a second path 21 in the second part 2 the second part 2 includes a passage 22 defined therein and a lock core 24 is received in the passage 22 a second threaded hole 28 is defined in an underside of the second part 2 and communicates with the second path 21 and the passage 22 a second protection member 29 is threadedly connected to the second threaded hole 28 a second slot 27 is defined in a top of the second part 27 a substantially u shaped reinforcement plate 3 has its two ends inserted into the first and second slots 15 27 which are in communication with the first and second paths 11 21 the first and second bolts 4 5 extending through the first and second paths 11 21 and the two ends of the reinforcement plate 3 which is connected across the two cantilever brake bosses al a positioning plate 31 is connected to the reinforcement plate 3 and the lock rod 14 is removably engaged with the positioning plate 31 as shown in fig1 to 13 when locking the bicycle lock the user removes the lock rod 14 from the positioning plate 31 and pivots the first part 1 and the lock rod 14 about.