Vintage Shimano Biopace SG oval chainring set. These are the harder wearing steel version which are not so common. Three rings SG-B 28, SG-B 38 and SG-B 48, being 28,38 and 48 teeth respectively. In generally very good condition, with usual shifting marks on the rear of the largest ring. The 38 tooth ring has 3 worn teeth as can be seen in the pictures, but there is plenty of life still left in these rings. Ideal for a nice retro build.