Road Traffic Act 1991
Road Traffic Act 1991 (c. 40)
The Highway Code - Motorcyclists 83 -88
83-88: Rules for motorcyclists : Directgov - Travel and transport
88
Additionally, when filtering in slow-moving traffic, take care and keep your speed low
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Urban motorcycling - Safe Filtering and Minimising risk in heavy traffic
In addition at traffic lights, passing the lead vehicle introduces the risk of the lights changing to green just as we level with the car, where as joining one or two cars back, represents a significantly lower risk.
If we do get to the front of the queue while the lights are still red, we will need to move off promptly to avoid being shunted from behind, once the lights have changed.