i too think that weight saved in the tires and rims is better than weight saved on the frame. i had to wheelsets for my track bike. same cog size cog on each. one was a really light rim and tubular tire. the other was an open pro with a heavier clincher tire. the tubular rims were noticeably easier to accelerate and to climb with.
also, race car engine builders always try to lose weight on the rotating asseembly within the motor and also on the flywheel so that the motor will rev quicker. same principle.
Jeff Piwonka Austin, Texas, USA
--- Jerome & Elizabeth Moos <jerrymoos@sbcglobal.net>
wrote:
> It's not a myth at all. A wheel with more mass far
> from the center of rotation, i.e. the rims and tire,
> does take more energy to accelerate to a given speed
> as you concede. By keeping its momentum better, you
> seem to imply that the rotationg energy of the
> heavier wheel can somehow be used to overcome the
> energy losses encountered, mostly the energy
> consumed driving the bike and rider against air
> resistance, and a much smaller energy consumption by
> friction at the tire contact patch.
>
> That's an interesting theory, and I'd be
> interested to hear a real expert analysis of that.
> I suppose an empirical experiment to test it would
> be to accelerate two wheels with the same overall
> mass and diameter, but different mass distribution,
> to the same RPM, then allow both to roll along the
> same smooth surface in an enclosed building and see
> if one rolls farther than the other.
>
> But even if that is true, in actual cycling it
> would only apply to a time trial. That is, if you
> are right, the time trialist with the heavier rims
> would have to use more energy to get up to top
> speed, but then need to use less enery to sustain
> that speed. The problem is most cycling on the road
> involves the use of brakes. So the extra energy of
> a heavier rims just means more energy dissipated at
> the brake pads each time one brakes to a lower
> speed. I still think an ounce on the rims is worth
> a pound on the frame. Schwinn seems to have
> believed that too. My filet brazed 1973 Schwinn
> Sports Tourer probably weighs close to 30 lbs, as
> Schwinn had a lifetime waranty on frames, and
> therefore tended to overbuild them. But the wheels
> are top quality stuff, Weinmann alloy rims on
> Normandy Competition hubs, keeping the weight low
> where it really counted - although actually they
> could have used heavier hubs, since those are close
> to the axle.
>
> Regards,
>
> Jerry Moos
> Big Spring, Texas, USA
>
> John Wood <braxton72@gmail.com> wrote:
> On Thu, Jul 3, 2008 at 4:26 AM, Neil Foddering
> wrote:
>
> >
> > I think that someone may have touched on this, but
> a phrase that sticks i
> > n my mind is "an ounce on the rim is worth a pound
> on the frame",
>
>
> Sorry to say that this is yet another myth that has
> been debunked in recent
> years. I'm sure there are others on the list that
> can explain it better
> than I can, but weight is weight regardless of where
> it's located. A
> heavier wheel will indeed take a bit more energy to
> accelerate, but will
> keep it's momentum better. For climbing, a lighter
> will help, only because
> it reduces overall bike weight. An ounce on the rim
> is worth an ounce on
> the frame. This has been much discussed on other
> forums.
>
>
> --
> John Wood
> Washington Island, Wisconsin, USA
>
>
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