A strap, for example for securing an accessory to a frame tube of a bicycle, comprises a band 2 of a resiliently extensible material which is provided with a buckle 8. The buckle 8 has an opening 14 through which a tail end 6 of the band 2 can be passed. An outer bar 17 of the buckle 8 defines an edge of the opening 14. A prong 18 is fixed to the outer bar 17, and can be engaged with any one of a series of holes 10 in the band 2 when the band is flexed over the outer bar 17 and pulled taut. The prong 18 has a contact surface 26 which is profiled to define a notch 34, 38 which serves to inhibit accidental slippage of the band 2 from the prong 18.