Don't worry. Your "new" UN91 bb's are likely over 15 years or older since leaving the Shimano factory. The grease inside has probably changed viscosity due to non-use. Cartridge bb's don't usually require a "ream and face" of the bb shell so if the cups are torqued to spec just attach cranks and ride. The spindle should spin smoothly after breaking in. My last UN91 wasn't torqued to spec and lasted over 30,000 miles. I only tossed it because I tossed the frame and couldn't get the cups loose easily.
On Sunday, January 15, 2023 at 1:52:56 PM UTC-5 Scott wrote: > Edit correction to my post, please. > > Second sentence of third paragraph of original post should read: > > When I turn the spindle by hand it is not smooth (definitely some > resistance and a tad sticky)*, unlike* the one I installed in Atlantis or > an uninstalled on. > > > > On Sunday, January 15, 2023 at 11:44:35 AM MST, 'Scott' via RBW Owners > Bunch <rbw-owne...@googlegroups.com> wrote: > > > Hey, Bunch: > > Pinging the group's knowledge for input/feedback on an issue I'm having > with an install of a new cartridge style BB in a new frame. > > I'm building a new Atlantis and Gus. I installed a new BB (Shimano XTR > UN91) in Atlantis and torqued to spec. It's butterlicious smooth. Installed > cranks and gave them a spin. It's what every man, woman, and child wants. > > I installed same BB (also new) in Gus and tightened to spec. When I turn > the spindle by hand it is not smooth (definitely some resistance and a tad > sticky) like the one I installed in Atlantis or an uninstalled one. Why is > that? I checked it before install, and it was butter smooth. I uninstalled > it from Gus, and it spins butter smooth. I reinstalled main body section to > spec, and it is butter smooth, no change. When I install the opposing cup > (Shimano calls it an adapter), at this point is when I begin to notice a > notable change in spindle rotation smoothness. > > I've ensured proper shell widths. And I've ensured shell/cartridge faces > are clean and blemish-free. > > Of note, opposing cup spins freely during install for about one third the > way to full seat. From there it spins freely part of rotation and not > freely otherwise. I can turn it by hand still using splined-tool, but there > is definitely resistance during part of the rotation. After I can't go any > further by hand, I fully seat with torque wrench. > > Could it be that the threads on either side of the shell are not exactly > coplanar, since threads are not continuous from one side of shell to the > other? > It shouldn't be a shell facing issue, because the opposing cup doesn't > interface with shell face. > > Confounding to me. There isn't much to installing a new cartridge style BB > into a new frame...screw it in. That's the problem, in part. There's > nothing to correct with install technique. I'd love to be wrong and get it > butter smooth like one in my Atlantis, for example. > > Please, share your thoughts as to what the source of issue may be and > recommended remedy! > > Scott in (I want it to be spring, summer, and fall) Montana > > > > > -- > You received this message because you are subscribed to a topic in the > Google Groups "RBW Owners Bunch" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/rbw-owners-bunch/7Uu5LBGsfxQ/unsubscribe > . > To unsubscribe from this group and all its topics, send an email to > rbw-owners-bun...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/rbw-owners-bunch/db5d0a09-b8cd-4433-9ffc-cce5be97fd4fn%40googlegroups.com > > <https://groups.google.com/d/msgid/rbw-owners-bunch/db5d0a09-b8cd-4433-9ffc-cce5be97fd4fn%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- 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 view this discussion on the web visit https://groups.google.com/d/msgid/rbw-owners-bunch/09282ccb-f552-4234-92b9-9dcc38b7825an%40googlegroups.com.
