Bike bells generally look & sound a bit ugly. But why? What if they looked sexy & sounded like an angel playing a glockenspiel? A bell with a beautiful tone, but also a remarkable style and choice of materials that embodies a rider’s personality. The Large Oi fits 23.8 to 31.8mm bars e.g. drop bar road bikes and some cruiser / commuters. The Small Oi fits 22.2mm bars e.g Mountain bike (near the grips), BMX & some old commuters. Please use the guide below, or ask your local Knog dealer if you are unsure which size is suitable for your bike.