Officers of Met Police were called at 4:27pm on Saturday (June 1) to Fore Street in Edmonton when they found members of the public providing first aid to the victim.
A 19-year-old man was detained from near the crime scene and subsequently arrested on suspicion of causing grievous bodily harm.
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The rider, believed to be in his 20s, and the arrested man were rushed to a North London hospital where their injuries were assessed as non-life threatening.
The Daily Mirror reported that the victim was attempting to stop his bicycle from being stolen when he was allegedly stabbed.
A video on social media, it said, showed a man pinned on the ground by a security guard as crowds of public gathered around the victim.
The police have urged anyone with information to call to them via 101 quoting reference CAD 5043/01Jul.