The culprits had also reportedly been posting their weapon-brandishing stunts on social media.
The two were carrying swords and knives on Tran Phu Street, Ha Dong District when they were detained by a traffic police team.
"When I saw the traffic police team, I got scared and turned around," said Le Tien Dat, who drove the motorbike.
Le Ba Truong, who sat behind Dat and held the sword, said he brought the weapon from home.
"I brought the sword for self-defense. If anyone beats my friends, we will beat them back," Truong said.
Truong and 14 other people had previously been detained by police after participating in a motorbike race through Chuong My District on July 29. They have all been allowed out on bail and are awaiting their trials.