Has anyone ever heard of a five stroke engine? Sounds crazy, right? Wrong. It is perhaps the most genius thing I've ever heard of! A five stroke engine is basically a four stroke engine with a separate cylinder that acts as an expansion chamber, but instead of just drawing gasses out of the cylinder, utilizes the heat of the exhaust in a fifth stroke, the extended expansion. This is a low pressure cylinder that uses the expansion of the hot exhaust gasses to add another power stroke, improving the efficiency and power to weight ratio of the engine. Now, what if someone put one of these on a bicycle? How cool would that be?