A majority of accidents happen when cars pull out of blind alleys, driveways, run stop signs or lights.
This may be true of the US, but the statistics do not bear it out in the UK. Over here over 70% of all motorbike accidents had no other vehicle involved, and when you look at fatal accidents, that figure rises to nearly 85%
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Back home in the UK I wouldn't even consider going out without a helmet on. Here in Bangkok I very rarely wear one, on the grounds that avoiding a crash is the best option, and to avoid one over here you need all your senses on full unrestricted alert.
I do wear full MX style body armour over here though, the number of times you catch your extremities on wing mirrors and other things is unbelievable
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At home draggin jeans and an armoured leather jacket suffice.