One option, if you commute by train, is to use an old bicycle for one leg of your journey and to lock it by the train station, either during the day or overnight.
The London Cycle Guides have a full list of stations which have cycle parking. Click on "London Route Maps" to find out more.
You can also order the guides by calling the Transport for London travel information line on 020 7222 1234.
For information about other on-street cycle parking contact your local authority.