Reading along with the thread I was recalling the differing degrees of finish I've seen on the four faces of a single square taper BB spindle and suspected that variance of tool marks on the facets of the right side tapers could produce the response to the crank bolt force resulting in slightly uneven seating. An error at that slight distance from the center of chainring rotation would sure be visible at the teeth.
Jan beat me to it, but I'd try removing the crank arm and reinstalling it on a different orientation to the spindle tapers. You have three more tries before ruling it out and hopefully some aluminum "smeared" onto or into the offending tool marks will produce a smoother more equal interface and the arm will seat more perfectly. Andy Cheatham Pittsburgh On Wednesday, September 26, 2018 at 1:16:46 PM UTC-4, William R. wrote: > > I've been following this thread and I'm surprised that we haven't heard > from Jan himself. I can share my experience and what I learned going > through it. When I first got my Rene Herse crankset and SKF bottom bracket > three years ago, I had a similar experience where the crank was wobbling > and I couldn't get the derailleur to trim silently. I would be riding and > looking down, I could see that the crank wasn't running true. It was > certainly frustrating considering how much money I had just spent! I > contacted Compass directly and spoke (via email) with Jan himself. First > off he stated how high the tolerances on the SKF bottom bracket and Herse > crankset are and how super rare it would be for the spider to not be true. > More likely was for the chainrings to get bent slightly in shipping and > easily fixed on the bike with vise grips (with a towel to protect the > beautiful finish of the rings) and lightly bending them back to true. Most > likely (and what I was doing wrong) was that something was wrong with with > the high tolerance of the interface between the crank and the SKF bottom > bracket. It was coming loose slightly, just enough to put a little wobble > in the rotation of the crank. To remedy this Jan told me that the interface > between the crank and bottom bracket should be totally clean of any type of > grease or lube and tightened to the correct torque. He suggested that I get > one of the Herse "peanut butter knife" crank bolt wrenches (a knock off the > old campy wrench for good reason). The length of wrench are ensures that > you get the bolts in the proper area of torque with out over or under > tightening. I did both things and haven't had a problem since. The problem > can also develop when the high tolerance of a new Herse crankset is mated > to a used and/or less high tolerance bottom bracket. If the interface > issues between the crank and bb are not recognized and fixed early on, > irepairable damage can be done to the crank. > > Hope this is helpful. > > Bill in Westchester, NY > -- 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 [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/rbw-owners-bunch. For more options, visit https://groups.google.com/d/optout.
