Police are working with the organisers of a mountain bike event planned for the Glyncorrwg Mountain Bike Centre in Port Talbot this weekend.
The Kona Mash-Up event is being held on Saturday.
A recent mountain bike event held at Margam Park was targeted by thieves.
Inspector Karl Eenmaa of the Port Talbot Neighbourhood Policing Team said: “This weekend will see hundreds of mountain bikers come to Glyncorrwg to enjoy the fantastic trails and facilities on offer which are now considered among the best in the UK.
“It is absolutely essential that all the visitors take every precaution available to them in order to keep their belongings safe. We also want to ensure that there is adequate security at the event. I have no doubt that there is an organised crime group targeting this area and these events to steal the expensive mountain bikes.
“Investigations into the previous incidents are ongoing and we are working with the event organisers to ensure that security is in place.”
Police are appealing for information on mountain bikes worth around £10,000 which have been stolen in Port Talbot.
A total of eight mountain bikes were stolen from a secure lock-up at the Afan Forest Park Visitor Centre at around 11.15pm on Tuesday, June 8.
Four of the bikes, worth around £4,000, were later found dumped in a hedge just off the A4107 road near the entrance to the village of Cynonville.
The remaining four remain outstanding and are described as follows:
2009 KONA 120 SUPREME, 18″ frame, white forks, mostly white frame with orange and red graphics, value £900.
2010 KONA CADABRA 18″ frame serial no. HOAH 12977, value £1,600
2010 KONA CADABRA 18″ frame serial no. HOAH 13193, value £1,700
2010 KONA CADABRA 20″ frame serial no. HOAH 13019, value £1,600
The above three bikes have white forks and red and silver frames.
Police are investigating the thefts and are appealing to anyone who saw any suspicious activity near the Afan Argoed visitor site to come forward.
The thefts follow an incident at Margam Park when nine specialist bikes worth around £30,000 were stolen at the National Mountain Bike Championships between Saturday 29th May and Sunday, May 30.
Anyone with information is asked to contact South Wales Police on 101 or Crimestoppers anonymously on 0800 555 111.
