I will hazzard a guess that as vehicular road users they are not lawfully allowed to except in some specific circumstances just the same as you and I in a car or on our motorcycles .....
T.C ......
Not that you would know ANY laws apply to them by watching their antics
In respect of centre solid white lines the rules are slightly different as it applies to drivers and riders of "Motor Vehicles" not cyclists.
It is one of the few rules that are different to the rest of us as they are for example obliged to comply with traffic lights and "Stop" and "Give Way" signs or lines as these refer to all vehicular traffic rather than motor vehicles.
It is just one of those anomalies.
But in the case of a crash and injury occurring, under civil law they might be deemed as having a large degree of contributory negligence (well they would if I was the investigator advising the court) and so a large proportion of their compensation would be lost under the rules of causation.
All depends on the circumstances and the actions of others involved of course.
