xroadcharlie

Think of our legs and crankset as a gas engines crank, pistons and connecting rods. At low power levels spinning the engine fast wastes power, hence a low idle speed is best. Keeping the engine at the lowest rpm for a given power is most efficient. Thats why today's cars have so many gears. But that too has it limitations

They can overheat, or break with too much stress, just like our legs become fatigued and fail. The key is to find the right balance between cardio capacity and muscle endurance. This is critical for racing, not so much for the recreational cyclist. The wild card for competitive racing is sometimes we must sacrifice efficiency so we have the power on tap for that sprint to the finish line, where max power trumps efficiency.

That balance is different for each person. Some of us have been blessed with great leg power and endurance, For them, a lower cadence might work better then spinning.