Dear Nicole &tc Perhaps cork or leather fender washers (as sold by Velo Orange, Rene Herse (Boulder), and others) at the rack mounting bolts would provide sufficient damping to deal with the shimmy, yet allow enough tightening torque on the bolts to prevent them from working loose over time due to road vibrations.
Fall comes to New Mexico; Smell the green chile a'roasting!!! Marc ______________________________________ On Sep 7, 5:33 pm, NME <nicolemea...@gmail.com> wrote: > Thank you all for your really insightful comments! I tried a few more > things, including some your suggestions -- made sure the wheels were > aligned, checked tire pressure, etc. > > I noticed that the problem was much worse when I was on smooth > asphalt, but would almost disappear when I was riding on gravel, > cobblestones, or bricked sidewalk, so it occurred to me that the > problem was this "harmonic" vibration -- not that the bike was out of > alignment, but that it was too perfectly aligned. So on a whim, I > *loosened* the bolts to the rack -- not enough that the rack wobbles > or is in danger of coming unscrewed, but just enough that there can be > some miniscule "give" between the rack and the frame. My idea was > that if I could disrupt the perfect transmission of this vibration, > then it wouldn't radiate to the front wheel, but would cancel itself > out.dear > > It was the exact opposite of DougP's suggestion and the opposite of my > original inclination, but it worked! It went from violent shimmy to > completely smooth. No shaking at any speed. > > Is this perhaps another version of the "self-restoring force" Ken was > talking about? (The maths are also beyond me.) In any case, if the > problem happens again in another context, I'll be sure to look into > "tire damping" (nice term) as a first resort! > > -- > > Thanks again, everyone! I'll finally be posting pictures of my AHH > soon, now that I've got it properly scratched up and broken in. Five > months in Berlin, and besides the daily commute, a few wonderful day > rides already, and and now some inn-to-inn rides planned for fall. > > Nicole > > P.S. in answer to Ken's question -- neither me nor my mechanic are > well-skilled. -- 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-bunch@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. -- 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-bunch@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.
