Speed wobble on ST1300 UK police model - Page 2

 

But it has an electric windshield!

I guess these machines will need steering dampers added on.  But if
Honda does that, they are admitting fault.

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 David Steuber wrote:


Sorry. Not even close. No cigar for you, David.

Steering dampers prevent "speed wobbles". The problem with the ST 1300 is
rightly understood as a
*high speed weave*.

"Speed wobbles" are something else, entirely. Speed wobbles occur when the
motorcycle is in the vertical position. They do not throw the rider off the
motorcycle, but they scare him.

In the case cited, the constable was thrown off his motorcycle and a car ran
over him.

Speed wobbles occur when the front tire contact patch is unweighted while
crossing bumps, railroad tracks, etc. The speed wobble occurs at such high
frequency ( 5 ~ 10 cycles per second ) the rider has no time to react, and
the speed wobble is over and done with.

When the front tire regains traction, the energy of the speed wobble is
absorbed into the chassis and the oscillations are quickly damped by inertia.

A steering damper will not prevent a high speed weave, because a high speed
weave involves more than just the oscillation of the forks around the
steering spindle.

High speed weaves tend to occur when the motorcycle is leaned over in a turn.

High speed weaves involve the whole chassis, so the oscillations around the
roll and yaw axis occur at a much slower frequency (about 1~3 cycles per
second). The amplitude of oscillation in the pitch axis is very small,
because the steering head jacking effect of waggling forks is small.

But the amplitude of the oscillations about the roll and yaw axis is
absolutely terrifying.

The rider can get out of the speed weave by leaning forward, rolling off the
throttle, and dragging the rear brake lightly.

A rider can also stop a speed weave by dropping his feet off the footpegs and
lowering the center of gravity, but he risks running over his foot if the
roll oscillations are extreme.

Before I completely gave up trying to ride my KLR600 off road, I had some
annoying crashes on dirt roads where the skinny front tire's minimal traction
prevented it from stabilizing the motorcycle above
15 or 20 mph. The center of gravity is just too high for the minimal traction.


I could ride in 2nd gear, but never in 3rd. To keep the motorcycle from
weaving violently, I had to roll off the throttle and drop my feet from the
footpegs.

The ST1300 police model has a high center of gravity, and the front tire
lacks enough traction to stabilize the chassis. A lower profile, wider, or
less pointy front tire is indicated. Or, a narrower rear tire might be fitted
to stop high speed weave by reducing traction at that end of the machine.

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