The pair tried to steal a Suzuki 125cc bike as the owner got off his bike to post some mail in the town centre on Monday shortly before 12.30pm.
However, the owner noticed the pair and began chasing them, but they got away on their own bike, riding off down Harrop Well Lane.
It is understood they then headed towards Castleford and were spotted near Xscape.
They are described as being around 5ft 8” tall, both of skinny build, wearing tracksuits and masks with no helmets.
Anyone with details is being asked to call police on 101 quoting reference number 13180376153 from Monday, July 30.