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Plastic retainer on UN73 bottom bracket?(5 posts)

Plastic retainer on UN73 bottom bracket?crestlinefarm
Jan 21, 2004 11:08 AM
I just bought a UN73 bottom bracket, and when I opened the box, the left hand retainer is plastic. Shouldn't this retainer be metal for a UN73 (Ultegra level), and does anyone think this will be a problem? I don't really care about how it looks, as long as the durability/longevity is similar between the plastic and metal retainers. I wouldn't think Shimano would switch if it created an obvious weakness. Thanks!
re: Plastic retainer on UN73 bottom bracket?Rusty Coggs
Jan 21, 2004 1:14 PM
I have had the plascic ones crack,but they still worked.
Did it start creaking when it cracked?crestlinefarm
Jan 22, 2004 9:29 AM
Sounds to me like it isn't a big deal, so I guess I'll keep an eye on it and cross that bridge if it cracks. I found it on clearance for $10 (no returns!) so I guess it's true that you sometimes get what you pay for!
UN73 is Ultegra level?czardonic
Jan 21, 2004 4:17 PM
Anyway, the cup is plastic for UN73s (and most other Shimano square-taper BBs I can find). The splined Ultegra BB has metal cups.

I wouldn't worry about the plastic, as long as it is installed correctly.
Unless Shimano changed the UN73 to make it cheaper,MR_GRUMPY
Jan 21, 2004 7:03 PM
you might have been given a bogus deal. UN71's and UN73's used to have all steel cups. The lower level UN50's and UN51's ( 105 level) had a plastic cup on one side to save money. If I bought such an item from a shop, and made sure that the label on the main part said UN73, I would think that the shop lost the steel cup and replaced it with a 105 cup.
Like I said, it's possible the Shimano got cheap, and are making all their UN73's like that now. I would check it out by looking at other BB's.