Kunshan "anti-killing case", the fatal intersection of two middle-aged people in a foreign land, what is the reason for the conflict between the two sides?

Causes of conflict between two middle-aged people in a foreign land in Kunshan anti-killing case. The tail of the original BMW vehicle and bicycle was scratched. At first, BMW's friends tried to move the bike, but there was a conflict. BMW owners began to punch and kick bicycle owners and took out their weapons. Then the murder weapon was accidentally dropped and picked up by the owner of the bicycle and killed.