Originally Posted by
cyclezen
Yes, Inertial energy is determined by the velocity (and mass) of the entire mass, but not a 'constant'...
why ? By Definition 'climbing' is a change in vector, hence 'Acceleration'
Mind Experiment (which could be done in 'reality).
So, maintaining same air and rolling resistance, same equipment/rider, you ride to a set velocity (speed) , on 'flat', stop pedaling, you will coast a certain time/distance...
same air and rolling resistance, same equipment/rider, you go on an up-slope and stop pedaling at the same velocity, you will coast a shorter time/distance...
going upslope is 'acceleration' - the inertial energy is dissipated/used faster, over a shorter time, which also determines distance... Gravitational acceleration.
The pull (acceleration) of gravity is a 'Constant' during all this, but when you 'climb' you are changing the 'vector' and now needing to overcome the 'acceleration of gravity'.
an example of calculation of this - lifting a 35kg object 1/2 meter... I'm lazy and the calculations are all done here:
How much work does it take to lift a 35 kg weight 1/2 m ?
I expect measurement or calculation of inertial stored energy will be spectacularly well below what is needed to climb 1 meter of road elevation.
rotational mass... is then also affected by gravity, - "
the rotational inertia of an object depends on its mass. It also depends on the distribution of that mass relative to the axis of rotation." more on this here: What is rotational inertia?
Anyway, differences in rotating masses are also involved in the gravitational effect.
Th
Yuri
You are confusing the issue between force and acceleration here. You are not overcoming "acceleration of gravity", you are overcoming the "Force" of gravity. Gravity only causes the mass to actually accelerate if you don't apply an opposing force. All that matters as far as the mass is concerned is the
net force acting on the body. The body can be accelerating, decelerating or moving at a constant speed depending on the net balance of those opposing forces.
If you want to accurately predict how fast a rider will climb up a hill, all you need to know is:-
1. Total mass of the bike + rider
2. Gradient of the hill
3. Rolling resistance of the tyres
4. Aerodynamic drag
5. Rider power output
The distribution of wheel mass is, to all intents and purposes, irrelevant to the result. I can't think of a model that even includes it as a parameter in such a calculation. Can you?
I'm not questioning the concept of rotational inertia and being an engineering grad I'm well aware of how to calculate it, but it is simply not relevant to your climbing speed. Lightweight wheels with low inertia feel nimble, accelerate more easily etc, etc. but none of this matters (except their overall weight) when you are plodding at a steady 5 mph up a steep hill.