Originally Posted by
McBTC
While there is not a lot of research in this are, the little that does exist supports going to less than 160 cranks even for longer legs.
Where did you read this? I've never heard of any studies to support it.
Originally Posted by
McBTC
Crank lengths in the 170s probably is no more ideal than longer versus shorter stroke gas engines or thinking carbo loading is necessary before a long ride.
This is certainly off-topic but shorter stroke length, within reason, is a better design. It allows higher rpm without excessive piston speed and allows for larger valves (due to the larger bore diameter) for better, more efficient breathing. The only reason for a long stroke is when tax laws are based on bore diameter (not just displacement) as the British laws were years ago or to make the engine more compact when there are packaging concerns.
Excessively short strokes, like F1 engines, do have issues with emissions due to extra surface area but for most uses, shorter is better. However, I have no reason to think that applies to crank length.