Not sure exactly what you mean. But every test I've seen shows the traditional chain is more efficient than a belt. The belt justifications I've seen are less

Not sure exactly what you mean. But every test I've seen shows the traditional chain is more efficient than a belt. The belt justifications I've seen are less maintenance, cleaner (no oil on clothes), and quieter. Never seen anyone claim it's more efficient. Thus almost all bikes and nearly all motorcycles use chains, the higher the performance the more likely they are to use chains. However electric bikes (where efficiency isn't as important) or harley motorcycles sometimes use belts. As do folding bikes where you might come in contact with the belt. But racing bikes or motorcycles are pretty much always chains.