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Old 11-13-2012, 12:01 PM   #467
Ed~
What, Me Worry?
 
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Joined: Sep 2010
Location: Bisbee, AZ
Oddometer: 332
Quote:
Originally Posted by Tracks1 View Post
I agree if the bike is in the tested stock configuration. However, having moved the CofG aft and thereby reduce the Margin (distance between the CofG and the Neutral point) will lower the speed of oscillation onset and increase its magnitude. It needs an increase in the Margin and a Damper. Fey was fine until the new Head Bearings were installed which reduced the steering friction. There is also the rear steering aerodynamic effect of the radius'd panniers in a cross wind gust.

If I recall correctly, Fey made a comment about how the bike was easier to turn after loading it with all of her gear. This is an indication of reduced Margin and lower stability.

Rule for dirt tires on hard surface roads...slow down or you will crash.

Rule for street tires on soft surface roads...slow down or you will crash.

Cheers,
David
I agree with what David has said but it's unlikely that the bags/mounting design will be changed anytime soon. And anyway, the frame flex for DR/KLR's when heavily loaded has a lot to do with the onset of such instability and that cannot be changed without major mods. It is, however, a good reason to consider soft-bags set up on the current racks that hugs the bike and reduces the lateral dimensions compared to hard bags. Soft bags not as convenient to pack however, quite aside from being pricey.

However, with regard to steering head bearings, an old bearing only gets notchy and doesn't provide more friction for the steering. New bearings only makes it smoother back and forth but will also make no difference on the friction compared to a old one. Proper torque on the bearings is what provides good friction and a reduced tendency for the handlebar/front wheel to "flop" back and forth freely when off center. That is most important to check, Fey.

This is commonly set by getting the bike off the ground to free the handlebar/front wheel. Tightening the torque nut until that loose ability for the steering to flop is gone. Then go on a test ride... nothing should feel out of the ordinary. Too tight is obvious because the rider will have to physically input on the bars to steer the bike to right up from even the smallest turn and feels terribly unnatural to ride that way.

After all is said and done, slowing down when riding a DR fully loaded is the only sure way not to experience a tank slapper again.
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Ed~ screwed with this post 11-13-2012 at 12:17 PM
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