Originally Posted by
cplager
If you are moving at a constant speed, then whatever rotational energy your wheels have they will keep. So you won't need to provide any extra energy to keep them moving at that speed.
When climbing hills, people are not generally accelerating, but trying to go a (relatively) constant speed, so you just need to worry about the energy needed to lift the rider, bike, and tires up the hill. And for that calculation, the 100 g of the tires is just as important as 100 g of twinkies you just ate at the last rest stop (o.k. they don't taste as good, but)...
If you are accelerating up a hill, then you the factor will be somewhere between 1 and 2 depending on the size of the hill and how fast you are accelerating.
Another way of deciding that it isn't the heaviness of the tires that matter:
If it were because the tires were heavy, then once you were at speed, you'd find that when you stopped pedaling, you'd roll faster and farther because of all of the energy stored in the rotation of the tires. While measurable, this effect isn't noticeable. On almost all of the tires that people are complaining about them being heavy, the roll-out distance will be shorter because of the increased rolling resistance.
you use clearly defined terms very loosely, to match you preception, which, of course, is seen through inherent poor vision.
Content in here describes acceleration and gravity succinctly:
http://en.wikipedia.org/wiki/Equivalence_principle
"...So in Newtonian physics, a person at rest on the surface of a (non-rotating) massive object is in an inertial frame of reference. These considerations suggest the following corollary to the equivalence principle, which Einstein formulated precisely in 1911:
Whenever an observer detects the local presence of a force that acts on all objects in direct proportion to the inertial mass of each object, that observer is in an accelerated frame of reference."
When changing 'gravity' acceleration happens.
If for simplification, one can remove aerodynamics and friction/rolling resistence, then simply, the pedal stroke you provide to travel uphill provides the change of force. When that mass no longer accelerates from the pedal stroke, you stop and reach equilibrium. This is also true on a plane where the force of gravity remains perfectly constant, you would travel at a constant speed, if it were not for friction (road/machine/aero). Basically a satellite which farts... If you were to move that satellite further away from earth's gravity, you'd have to accelerate it. Same as climbing a hill...
As one rides along on a flat road, you are constantly accelerating, because you need to overcome, friction (road/machine/aero). WHich is why MASS (weight in gravitational field) is important. Momentum is quickly eaten up by the friction forces, so the best approach is to minimize MASS, and reduce friction however possible, so that the amount of force you need to create the needed acceleration is minimized.
Tire/tube/wheel weight/mass matters a lot, all the time, as does the butterfat we're all draggin along...
The human condition is to screw with the Tire/tube/wheel weight/mass more than the other stuff... but anything we do is all good.
EDIT: If we were on Barzoom it would all be easier... and that third slice of pizza wouldn;t matter as much. Or riding those Marathon truck tahrs...