Two men had their off-road motorbikes stolen from them at knifepoint as they walked along an Arnold road.
The men were on Bestwood Lodge Drive when the robbery happened at around 6.25pm on Saturday, May 4.
Police say a group of about six or seven boys, who were wearing face coverings and dark-coloured clothing, approached the victims.
They are described as being two black youths and the others white youths, all aged between 13 and 18.
One of the offenders threatened one of the victims with a knife before his bike was taken.
The same offender then approached the second victim who was punched by another of the suspects.
He then let go of his bike before the offenders rode off with both bikes.
The bikes, as pictured, are a green Kawasaki KX80 and a yellow Suzuki RM85. Both bikes have kick start engines not requiring a key.
Detective Sergeant Luke Todd said: "Our investigation is ongoing, including house-to-house enquiries and exploring CCTV opportunities.
"We’re appealing for anyone with any information about the incident and anyone who may know of the whereabouts of these distinctive bikes to get in contact with us by calling 101.
"We believe the bikes have been seen in the Bulwell area since the incident so we’d urge anyone who may have seen them to get in touch."
Anyone with any information is urged to call Nottinghamshire Police on 101, quoting incident number 741 of 4 May 2019, or Crimestoppers anonymously on 0800 555 111.
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