Joined: Jun 2013
Posts: 111
Likes: 1
From: Yonkers, NY
Bikes: 74 Raleigh Grand Prix fixie,85 League Fuji w/ flat bars, 87 Cannondale ST400, League Fuji Fixie, Raleigh Pursuit Fixie, 93 Cannondale M500, Kabuki Submariner 12, 90 Fuji Suncrest, Peugeot Mixte project
Sorry, I mistakenly started a new string when I should have added it to this one. This problem with the Shimano BB-UN55 is real, the concerns are not OCD or excessive and flip answers are not helpful. The concept that the NDS cap will shrink to hug the cartridge is nonsense. If you can thread it in by hand, how can it "scrunch"? Also, aluminum is not flexible in that way. The clearance between the NDS cup and cartridge body is excessive, period. This slop will allow the cartridge to move up and down as you pedal. The laws of mechanical engineering are not subject to revision by rhetoric or marketing.
Sorry for ranting. Below is my post, repeated.
I'm a Clydesdale and I need a strong BB. Can't afford to put Phil Woods on my 5 bikes.
Recently I bought a shimano BB-UN55, happy that they have replaced the plastic left cap with aluminum, although I would have preferred steel. I immediately noticed that the left side cap fit VERY loosely on the cartridge. There was more play in this than I have ever experienced in an NDS BB cap. I called Shimano customer service and they said not to worry about it. I was skeptical but installed the bottom bracket anyway and kept an eye on it. I was properly torqued to 55 ft.lbs. It immediately worked loose, so I reinstalled it with blue thread locker. Soon, it began creaking like crazy. This is a 27 year aluminum frame so I’m worried about the threads in the shell. The BB55 left cap which does not hold the cartridge firmly parallel to the shell allows it to flex. I confirmed this by putting a run of plumbers’ teflon tape around the cartridge as a guage of whether there was movement and where. It was abraded away at the top and bottom indicating to me that the cartridge was lashing up and down while riding. Had the NDS cap fit snugly on the cartridge, it would have conrolled this movement. I replaced the aluminum left cap with a leftover steel Tange NDS cap which hugs the cartridge snugly. It seems to be OK.
I might use the Tange LL-3922 BB from now on. They only cost a couple of dollars more and I think all steel is a more robust way to go.