Joshua Williams was convicted of murder and conspiracy to rob
A man has been found guilty of murdering a 15-year-old cyclist during an attempt to steal his bike.
Joshua Williams, 18, was part of a group which attacked Alan Cartwright as he "innocently" rode along Caledonian Road, in Islington, on 27 February.
Williams, who had denied murder, lashed out at Alan, delivering a single stab wound, the Old Bailey heard.
He had claimed to be at a youth club at the time of the attack, but jurors rejected his explanation.
Williams, of Holloway Road, north London, was convicted of murder and conspiracy to rob.
During trial, it emerged he had been on police bail on suspicion of possessing a 4in (10cm) lock knife, although he was never charged.
He will be sentenced on Friday alongside Shaquille Roberts ,18, and a 16-year-old who previously admitted the bicycle robbery.
Alan was cycling with five friends on the evening of the attack when the trio intercepted them, the court heard.
Alan Cartwright was cycling with friends when he was targeted by a group of robbers
They stepped out in front of the cyclists and managed to take two bikes, before Williams approached Alan and swung a knife at his chest in a "deliberate and gratuitous" stabbing.
Alan managed to cycle on for a short distance before collapsing. He was pronounced dead a short time later.
Williams was identified in a YouTube comment on CCTV footage after police posted it online, jurors heard.
On 4 March, he went to Islington police station with his parents to hand himself in, the prosecution told the court.
His mother told a police officer it was about the incident in Caledonian Road, saying: "Yes, he's involved, he did it."
Alan Cartwright's family said he was amazing and the best brother
Alan Cartwright's family has called for more police stop and searches and tougher sentences to deter young people from possessing knives.
Sister Cherrie Ives, 22, said: "Now we have gone through it, we have noticed there is a lot more knife crime. It's all down to stop and searches. There should be more."
Alan's father, Alan Cartwright senior, 44, and his mother Michelle Watson, 40, said: "Alan was just a normal 15-year-old boy - loved his bikes, his family, being out with his friends. He was just a funny little kid, at the end of the day."
His sister added: "He was amazing, honestly. I know everybody says their little brothers are little rats.
"We wouldn't change him for the world. The best brother."
Ms Watson said the effect of his death had been "devastating" for the family.
She said: "Life without Al is killing me as his mum.
"He was our loving boy - our only son."
However, during his defence, Williams claimed he was at a youth club and only went to the police station to deny his involvement, a claim his parents and brother backed up in their evidence.
But prosecutor Jonathan Rees QC told jurors Williams' alibi was in tatters and his family had "decided to abandon their principles to support him in his lies to the court".
Jurors took three hours to find him guilty.
The attack on Alan Cartwright on Caledonian Road, Islington, was captured on CCTV
Det Ch Insp Chris Jones, from the Met Police, said Alan "was not in the 'wrong place at the wrong time', but had crossed paths with Williams, who was armed with a knife and "clearly thought nothing of using it".
Alan is one of 10 teenagers who have been fatally stabbed in the capital this year.
He was killed close to the spot where 16-year-old Ben Kinsella was stabbed to death eight years ago, which prompted a high-profile anti-knife campaign led by his sister, EastEnders actress Brooke Kinsella.