Security marking and police tagging for bikes
Many insurance companies will ask you to security tag your cycle.
Even if you don’t insure your cycle this is a good idea, as it means you have full record of your cycle on file somewhere, which could help you to prove it is yours if it is stolen and then found by the police.
The most important thing to keep a note of is your frame number as this is unique to your bicycle.
Your frame number will usually be stamped on the underneath of your bottom bracket, which is where the pedals are attached, or on the rear fork ends where the back wheel slots in.
It’s a good idea to keep a photograph of your bike with a note of details like frame number, model number, make, colour, and any special details.
Getting your bicycle visibly security marked and registered acts as a deterrent to potential cycle thieves as they know your bike is traceable, and reduces your chances of being a victim of cycle theft. And if it should be stolen, registered bicycles and far more likely to be reunited with their rightful owners.
London’s police agencies often hold free cycle marking and registration days. Find out where and when the next events are:
http://www.met.police.uk/transport/cycle_marking.html
There re several tagging and registration schemes available. The Metropolitan Police use Bikeregister , other providers include Immobilise and Dataag. Schemes like Bikeregister and Immobilise allow you to register for free. They charge for stickers and tags that can be hidden inside the frame but are readable by a detector.
Some police stations will stamp your postcode and house number or name onto your bike and keep an electronic record of your details.
You could also use ultra-violet markings as police can check for these when stolen bikes are found. Call local police stations in your area to see if any of them offer this service.