Not locks, but security against terrorism.
The other day on the news I heard about some fake grenades being tossed at an embassy in NY. The culprit may have been riding a bicycle.
Today a terrorist rode a bicycle in order to kill Iraqi police.
What would happen if bicycles became a common mode of transport for evildoers? They are maneuverable and very rapid, by an expert rider. See e.g. 'Messengers on Crack'-type youtube video.