Hello a while back a plastic disk around my bike chain snapped in half while I was biking. I think it's called a chainring guard. How do I find out the size
Chain Guard - Plastic
CHAIN GUARD IDEAL FOR FOLDING BIKES OR JUNIOR CYCLES 180mm DIA FOR 36/38 TEETH CHAINWHEEL,SHORT LENGTH 290mm. SHIMANO NEXUS COMPATIBLE : Amazon.co.uk: Sports & Outdoors