Originally Posted by
Velocirapture
By way of analogy, if a plank is lying on the floor, with a weight in the middle of it, it will take a certain amount of energy to lift up one end of that plank. If you put the weight closer to you, and lift up the end again (by the same distance), it will be more difficult, becuase your lever is shorter (even although your plank is not shorter).
Same thing with the bigger chainring, imo.
good analogy- except not only does it not illustrate your point- but i think it backs up mine.
as you have written it- it is easier to move the plank if the weight is near the pivot point- what you are leaving out is that since the plank is moved the same distance with the longer lever the weight moves a shorter distance.. this beautifully explains differences in total Gear Inches and or changes in crank length and how those affect the system- but does not explain how a gear could "feel easier" while accomplishing the same work... yes the work you did was easier, but you did less of it..
in this example:
i think we all agree that our lever is an 81" drive train. whether accomplished by 48x16 or 51x17. I think we all agree that at any given crank RPM wheel speed will be the same on either system.
the "weight" is the force acting against the drive train. in this case that is the wheel. the wheel creates almost all of the resisting force against the cranks..
so if at same RPM's either drive train is spinning the wheel the same speed and creating the same opposing force on the drive train... what changes to make it "more difficult"? or less difficult?
the "weights" are in the same place on the "Plank" and the Plank is moving the same distance and so are the weights...