Good, then maybe we have found the real expert in this that we have always lacked. Is it not true that the force required to achieve angular acceleration or deceleration is a function both of the mass of the rotating object, and of its distance from the axis of rotation? And is it not also true that because the frame attaches to the wheels at the hub axle, that it acts at zero distance in respect to angular acceleration? This has always, as far as I know, been the basis for those who asserted that the weight of the rims and tires was crucial, while the weight of the frame was inconsequential, at least for acceleration and braking. This fits with the Classical Mechanics I studied, but I took only the few courses required for an engineering degree, so if you, as an instructor in the subject, can point out a fallacy in this common interpretation of mechanics, I'd be very interested to hear it.
Regards,
Jerry Moos Big Spring, TX
Sergio Servadio <servadio@df.unipi.it> wrote:
Jerome & Elizabeth Moos wrote:
>We've had this dicussion before, but it goes far beyond the wheels part in determining total bike weight. The rims and tires have a large moment arm about the axis of rotation (the hub axle), while everything else, including the frame, has essentially zero moment arm, so when it comes to accelerating and braking, rim weight counts for everything, while frame weight counts for nothing.
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Pardon me, I can read no further.
If not, because I teach Classical Mechanics.
Sergio
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