Here is the latest guidance on regulations about pedal bicycles lighting taken from the Department for Transport website.
 
 1. The use of lighting and reflectors on pedal bicycles is regulated under the Road Vehicles Lighting Regulations 1989, as amended. The most recent amendment is Statutory Instrument SI 2005 No. 2559 which came into force on October 23rd 2005. 

2. The main effect of the new Regulations was to permit flashing lights on pedal cycles. The flashing lights do however have to conform to certain requirements which are elaborated below.
 
 Obligatory Lighting and Reflectors 
3. Any cycle which is used during the hours of darkness or during periods of poor visibility MUST be fitted with the following: 

• white front light 
• red rear light 
• red rear reflector 
• amber/yellow pedal reflectors - front and rear on each pedal. 

4. The lamps may be steady or flashing, or a mixture - e.g. steady at the front and flashing at the rear. A steady light is recommended at the front when the cycle is used in areas without good street lighting. 

5. If either of the lights is capable of emitting a steady light, then it must conform to BS 6102-3 and be marked accordingly, even if used in flashing mode. 

6. Purely flashing lights are not required to conform to BS6102-3, but the flash rate must be between 60 and 240 equal flashes per minute (1-4 per second) and the luminous intensity must be at least 4 candela. (This should be advised by the manufacturer). 

7. The pedal reflectors and rear reflector must conform to BS 6102-2. 

8. Lights and reflectors not conforming to the BS, but conforming to a corresponding standard of another EC country and marked accordingly, are considered to comply as long as that standard provides an equivalent level of safety. 

9. Lights are NOT required to be fitted on a bicycle at the point of sale - but IF they are fitted, then they must comply with these regulations.
 
Optional lamps and reflectors
10. Additional lighting to the above mentioned obligatory lights is permitted under certain conditions: 

• It must not dazzle other road users 
• It must be the correct colour (white to front, red to rear) 
• If it flashes it must conform to the required flash rate (1-4 equal flashes per second) 

11. Optional lights are not required to conform to BS 6102-3 and there is no minimum level of intensity. So for example, on the rear of the cycle a cyclist may wish to have both a steady red lamp which conforms to BS 6102-3 and an additional flashing lamp which is not meeting the minimum level of 4 candela.
 
Exemptions from the Regulations 
12. The only case of exemption from regulations is for cycles which are used ONLY in good visibility during daytime. These cycles are not required to be fitted with lights.
 
Application and enforcement of the Regulations
13. The Regulations concern the construction and use of bicycles. Bicycle and lamp manufacturers, importers, retailers and riders should all ensure that they are familiar with the law. 

14. For non-lighting construction and use aspects of bicycle safety such as brakes, other regulations are in force - The Pedal Cycles (Construction and Use) Regulations 1983 (Statutory Instrument 1983 No. 1176). 

15. In addition, at the point of first sale the bicycle must comply with The Pedal Bicycles (Safety) Regulations 2003 (Statutory Instrument 2003 No.1101). 

16. The Regulations apply to mainland Great Britain but not Northern Ireland. They are made under powers provided by the Road Traffic Act 1988. Enforcement is a matter for the Police.
 
Additional information and advice
17. Copies of Regulations are available from: 

The Stationery Office
The Publications Centre
PO Box 276 Tel: 0870 600 5522
London Website: http://www.opsi.gov.uk
SW8 5DT Virtual Bookstore: http://www.tso.co.uk


18. Further information and advice about the regulations may be obtained from:

Transport Technology and Standards Division 6 
The Department for Transport
Zone 2/06, Great Minster House 

76 Marsham Street Tel: 020 7944 2078
London Fax: 020 7944 2196
SW1P 4DR 

Issued November 2005