Remember kids... always wear a helmet. (The almighty bikeradar helmet thread)

As I said further up there^^^ Contributory negligence has nothing to do with establishing fault for an accident occuring in the first place, it is about the degree to which compensation may be reduced due to any actions by the injured party which may have contributed to the level of injuries sustained.

In the incident mentioned in the article, the motorcyclist was judged to be at fault, that is, to have caused the accident. The fact that the rider was not wearing a helmet was then a factor in determining the level of damages that would be awarded to the party not at fault, in this case the cyclist. These are two completely separate decisions which should not be confused.

The Highway Code states that cyclists should wear a helmet. You do not have to, but no one can legitimately claim that the wearing of a helmet is something that they have been encouraged to do, which is why a helmet can be brought into consideration. Body armour, as mentioned above, is not something that is widely or expected to be worn on a bicycle on the road, so it is not considered.

A bike on British roads is required to have two, independent braking systems. You are correct to say that a fixed wheel is recognised as a braking system but for a bike to be legal for road use you still need another (and no, two legs do not count!). Similarly, a singlespeed needs a brake front and rear to be legal, it scares me how many riders on singlepeeds only have a front brake (what are you going to do when the cable frays and snaps on you?).

If a car driver caused an accident then they caused the accident, regardless of the state of your bicycle. However, while the issue of brakes may not have anything to do with establishing the cause of an accident, again, it may be taken into account in determining the level of damages awarded.

Cheers for the info.