Bill, et al,
I'm going to copy the MC chassis list for some other opinions, but I'll give you
mine;
The question is whether the added gyroscopic effect of heavy wheels would be an
advantage for a LSR bike, or as with other sorts of competition is it still
better
to have light components?
I would stay with the idea of light wheels, by instinct. They help the
suspension,
which isn't just to ride over perpendicular bumps, but will also help in
minimizing
the effect of off-center impacts that would initiate any occillation. You could
say
that a lighter wheel might deflect easier, but the result will be easier to
'tame',
by trail or a steering damper.
I don't see instability at speed as due to not enough flywheel effect.
(cross-winds; not sure but that might be just as much COG.)
Over-all I still think light wheels helping the suspension work would stay in
better
contact. There is also the easier rotation to accelerate.
Finally, don't forget about the basic effects of rake and especially trail.
Ideas?
Cheers,
Rick
rtmack wrote:
> Bill:
> these points are all quite logical and well thought-out. Making me think some
> more about my notion of heavy LSR bike wheels (at least w/ resp. to the
>front).
> Do you know of a published engineering study of speed-wobble causes/ effects/
> remediation? Also, I didn't receive Jon's response to your original. Is in
>not
> for public consumption?
> Another problem w/heavy wheels (for suspended vehicles) is the slower
>suspension
> response due to the inertia of the unsprung weight. Everything in design is
> compromise. Still trying to sort out those compromises before I decide what
>to
> build.
> Russ Mack
>
> ardunbill@webtv.net wrote:
>
> > Hi Folks, last week one or two of us kicked this around a little bit,
> > since someone theorized that heavier-than-normal wheels would be
> > beneficial to the stability of a LSR bike.
> >
> > Unfortunately, no-one among the 200 mph bike riders has yet commented,
> > so the point is moot so far.
> >
> > >From my observation, most if not all the fast LSR bikes use production
> > wheels or custom replacements of about the same weight, and since they
> > have been satisfactory for many decades, people see no reason to change
> > them.
> >
> > >From reading, I gather that traditional speed-wobble(front wheel and
> > fork oscillation, perhaps from lock to lock), which can easily cause a
> > wreck, is still a threat to LSR bikes today, as it has been from time
> > immemorial. The best answer is still an effective steering damper.
> >
> > In 45 years of motorcycling I can tell you what I've learned about
> > speed-wobble. It seems clear to me that the heavier the front wheel,
> > the more serious the threat of wobble. I attribute this to the pendulum
> > effect of the oscillating wheel, and if the fork and fender, headlight
> > assy., etc. are also heavy, they aggravate the wobble, once it has
> > started from any little bump on the road that strikes the tire off
> > center, when the tire, as it is supposed to do, tries to center itself
> > again.
> >
> > Another design feature that seems to give the inclination to wobble is
> > heavy drum or disc brake assys. on only one side of the front wheel.
> > When this is present, every bump the wheel goes over makes it "kick" to
> > the side a little from the inertia of the brake parts. When this is
> > combined with the other features mentioned before, you have a wobble
> > always lying in wait. Many years ago I had such a bike, made by a
> > famous Japanese company. I made it manageable (the bike HAD many
> > virtues) by the addition of an aftermarket hydraulic steering damper.
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