I rode motorcycles about 30 years ago, and there was an aftermarket product that was seen as having the potential to help - the adjustable hydraulic steering damper. It was a miniature version of a car shock absorber, looking about as large around as a tailgate lifter off of a modern car. They often had an adjuster knob so you could find your sweet spot. On my mid-'70s Suzuki triples I never really saw much of a shimmy problem, plus I was way too cheap to buy anything extra back then. But I rode with owners of BMWs (in some cases the short wheelbase ones), Triumphs, Nortons, Vincents, Ducatis, and just about anything else. For the record, the Suzukis did keep up, but not in raw speed.
Back to the topic, those who used the damper said it did actually reduce speed wobble and increase their confidence in their bikes. Based on these stories that I recall, I would assume that the apparent effectiveness of a needle bearing headset is in fact based on adding drag to the function of the headset bearings. One way to test the effectiveness of added drag would be to set up a bike that has shimmy problems with a low-cost ball bearing headset and ride it at settings that have differing degrees of drag. Another way to add drag might be to add rubber wraps around the headset upper or lower bearing sets, something like a Lizard Skin outer headset water shield. I don't have much problem with shimmy, so I don't really have the starting point. But maybe someone might want to try this? On Fri, Dec 10, 2010 at 11:10 PM, <stanwas...@bellsouth.net> wrote: > I worked in a multi line motorcycle shop from '85 - '95, and have been > happily riding motorcycles and bicycles for many, many years. Not > surprisingly, motorcycles experience a similar phenomenon Because of the > greater vehicle mass and higher speeds, a simple wobble or shimmy can > quickly become what is referred to as a dreaded high speed wobble or "tank > slapper". I have a few friends who have experienced the latter -one fair > outcome, all the rest terrible. I have only experienced a minor decel > wobble on a beloved old "Airhead" BMW myself. > > Just as with bicycles, there is no one answer. Correct steering head > bearing adjustment is critical, but not the magic bullet. Proper rear fork > (swingarm) bearing adjustment,especially on the aforementioned "Airhead" > BMW's, frame alignment, tire selection, tire air pressure, load placement > etc. are also important to eliminating the problem. (Sound familiar?) > > Most of the folks I spoke with complained of what is referred to as a decel > wobble. That is, after leaving go of the handlebar and as the bike loses > ground speed, a slight wobble would occur. This minor wobble can get out of > hand quickly if not corrected. The correction is to *gently* return ones > hands back where they belonged. A decel wobble typically occurs around > 40ish mph. Having experienced it myself, I assure you I wasn't being flip > when I would suggest to folks that there was really no good reason for > removing ones hands from the controls of a single track vehicle until it > came to a stop. Then I would run through the litany of checks and > adjustments that may correct the problem. > > Some time ago I read somewhere, here perhaps, that a possible technique for > eliminating a shimmy on a bicycle was to gently apply pressure to the top > tube with one's knee, assuming one could not be bothered to return ones > hands to the bars. I can't remember which of my three bikes exhibit a > shimmy with hands removed, but the other two do not. In my experience with > whichever bike it is, I have found that to be effective in eliminating the > shimmy. Of course, not removing my paws from the bars stops the problem > from occurring in the first place. > > For reference, some of you may find David L. Hough's "Proficient > Motorcycling" an interesting read. I have been riding bicycles since 1961 > and motorcycles since 1966. I always thought I knew what I was doing until > I read David's book. I thing you will find that much of the information > presented in that book regarding handling readily applies to bicycles. > > Take care folks. > > Stan > Columbia, SC > > > > -- > You received this message because you are subscribed to the Google Groups > "RBW Owners Bunch" group. > To post to this group, send email to rbw-owners-bu...@googlegroups.com. > To unsubscribe from this group, send email to > rbw-owners-bunch+unsubscr...@googlegroups.com<rbw-owners-bunch%2bunsubscr...@googlegroups.com> > . > For more options, visit this group at > http://groups.google.com/group/rbw-owners-bunch?hl=en. > -- Ken Freeman Ann Arbor, MI USA -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
