The use of motorcycles is prohibited if:

Explanation

If the safety bars (arches) provided for in the motorcycle's structure are absent.

Safety arches (crash bars) are part of the motorcycle's approved structure, and removing them — usually done for looks or to save weight — prohibits operation of the motorcycle. The criterion is that the manufacturer provided for them; if they are provided for, they must be in place.

Their function becomes apparent at the moment of a fall: a fallen motorcycle slides with its whole weight over the rider's leg. A safety arch creates a gap between the hot, heavy body and the rider's leg and takes the sliding energy on metal rather than on bone. It also prevents the fuel tank from being crushed and petrol leaking onto the hot engine.

The second option is this chapter's numerical trap. The permitted residual tread depth depends on the vehicle type: for a motorcycle the minimum is 0.8 mm, for a passenger car 1.6 mm and for a bus 2 mm. So 1.6 mm on a motorcycle is not only permitted but twice the legal limit. The common mistake is to generalise the figure 1.6, memorised for passenger cars, to every vehicle. Remember these three figures separately; they will come at you again in several more questions in this same chapter.

• 1.6 mm is the limit for passenger car tyres; for a motorcycle the permitted minimum is 0.8 mm, so a tread of 1.6 mm sits at a safe margin above the legal limit and is no offence. • Since the second item does not count as a defect, the combined option is ruled out too.

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