This is interesting, and illustrates the difficulty of dealing with shimmy. I use the Tubus Duo low rider (no hoop, just 2 loose pieces) and have loaded it with Ortleib large panniers (10-12 lbs each). Above that is a Nitto small front rack supporting an Acorn boxy rando bag (the early, smaller one), usually stuffed full if traveling. No rear bag, just a seat wedge with small tools, tube, etc.. This set-up has never shimmied.
A couple of possible variables from Clayton's set-up: my Atlantis has a 40 mm trail fork (stock is around 65 mm) and the IRD roller bearing headset. Depending on who you believe, lowering trail either magnifies or reduces the tendency to shimmy (helpful, no?) but consensus is the roller bearing headset has more drag & so may dampen oscillation, helping reduce shimmy. I agree with Clayton's hypothesis about rack wiggle & fork twist. Since shimmy is an oscillation, minor movements could set up major reactions. Like Clayton, my ride was more stable once I started loading the front, even with my old junky, definitely flexy aluminum low rider, stock fork & headset. I did still encounter shimmy. The randomness of it spurred me on to look for a reliable solution. dougP On Saturday, May 30, 2015 at 8:32:07 AM UTC-7, Clayton wrote: > > I was troubled by severe shimmy on my old Atlantis. I had a Nitto small >> front rack with a Tubus low rider. No matter how I changed the weight, it >> persisted. I bought a Nitto big front rack from Riv and the shimmy >> disappeared. For years I resisted the voices that said to load the front. >> Once I did, no prob. I have a theory that the Tubus front rack and others >> of the ilk, are too flexible laterally (not the rears, they are >> triangulated). Between the fork and rack oscillation dance, wibblewobbles >> raise their heads and make one nervous. The load yaws on the flexible rack, >> twisting the fork a bit, which hits the right oscillation frequency >> and..... > > > Claytonious Q > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch. For more options, visit https://groups.google.com/d/optout.
