Chain Rider Set Product Type Chain Rider Set For Chain Number 40 For Number of Strands Single For Chain Pitch 1/2 in Chain Rider Width 48 mm Idler Bolt Thread Size M10 Idler Hole System of Measurement Metric Length through Bore 55 mm Number of Chain Riders 1 Standards ANSI DIN 8187 ISO 08 B-1 Bearing Closure Double Shielded Bore Diameter 8 1/2 mm Chain Number 40 Compatible with Brand Rosta Compatible with Series 15-18