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What's are the differences between UN-54, UN-50 bbs?

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What's are the differences between UN-54, UN-50 bbs?

Old 12-19-09, 11:46 AM
  #1  
Sincitycycler
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What's are the differences between UN-54, UN-50 bbs?

Also, why do the 54's have those plastic cups? Isn't the aluminum one better?
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Old 12-19-09, 11:54 AM
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I run a UN54 that was outfitted with an aluminum cup and it was nothing but trouble. It constantly came loose and had a tendency to squeak, I swapped it out for a plastic cup and all was good.
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Old 12-19-09, 12:08 PM
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The UN-54 has a hollow axle. I have one in my cyclocross commuter. The plastic is holding up quite well Just remember, not all plastics are equal. As long as you don't ride through bottom bracket deep water, it should last a long, long time.
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Old 12-19-09, 01:29 PM
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IMHO, the plastic is better because it gives/flexes and allows the UN54 to work fine even if the frame's bb isn't faced perfectly.
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Old 12-19-09, 03:32 PM
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Originally Posted by Mr IGH View Post
IMHO, the plastic is better because it gives/flexes and allows the UN54 to work fine even if the frame's bb isn't faced perfectly.
Yup, I've never had a problem with the plastic. UN54 will last a good long time provided you're not riding through swamps.
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Old 12-19-09, 04:21 PM
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Originally Posted by Mr IGH View Post
IMHO, the plastic is better because it gives/flexes and allows the UN54 to work fine even if the frame's bb isn't faced perfectly.
You just made this up.

The plastic cup doesn't handle extremely bad shell facing (because that's what it takes to really cause a problem) than the lipless metal cup.
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Old 12-19-09, 07:14 PM
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The only "trick" to using bottom brackets with plastic nds cups is to install the cartridge (drive side) unit first, then install the plastic cup just finger tight. Finally tighten the cartridge side to full to torque and tighten the plastic cup snugly but don't go nuts.

Removal requires removing the drive side cartridge FIRST. Then remove the plastic nds cup. Do not try to remove the plastic cup first.
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Old 12-20-09, 08:50 AM
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Originally Posted by operator View Post
You just made this up....
"....Smooooooooth, Operator, coast-to-coast..." I hope someday we can meet in person so you can feel my love
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Old 12-20-09, 12:33 PM
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Originally Posted by HillRider View Post
The only "trick" to using bottom brackets with plastic nds cups is to install the cartridge (drive side) unit first, then install the plastic cup just finger tight. Finally tighten the cartridge side to full to torque and tighten the plastic cup snugly but don't go nuts.
I wish I had known this about two weeks ago. I'm no expert, but the tech sheet which came with a UN54 I installed recently was this one: https://techdocs.shimano.com/media/te...9830677388.pdf. I read it to mean I should torque the plastic side to 50-70 Nm. I did this and it survived but about a week later I noticed the plastic cup had cracked. I replaced it with a "Problem Solvers Up-Cup" replacement left cup.
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Old 12-20-09, 02:31 PM
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Originally Posted by mthomas View Post
I wish I had known this about two weeks ago. I'm no expert, but the tech sheet which came with a UN54 I installed recently was this one: https://techdocs.shimano.com/media/te...9830677388.pdf. I read it to mean I should torque the plastic side to 50-70 Nm. I did this and it survived but about a week later I noticed the plastic cup had cracked. I replaced it with a "Problem Solvers Up-Cup" replacement left cup.
I did the same exact thing, twice in fact. That's why I came up with my current method.
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Old 12-20-09, 03:05 PM
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Originally Posted by HillRider View Post
I did the same exact thing, twice in fact. That's why I came up with my current method.
That instruction sheet is incomplete garbage. Standard way of installing 2 piece bb's is to run both cups 90% of the way then drive side in then left side all the way. And it's well documented that the plastic cup requires substantially less torque than the metal version. Not sure why any of this is surprising to anyone.
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Old 12-20-09, 03:14 PM
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Originally Posted by operator View Post
Not sure why any of this is surprising to anyone.
I'm not surprised. Some of us dream at night about sexy girls/boys/sheep. Or dream of being a rock star. So forth. Only a few great ones dream about the minor technical variations in different bottom-brackets.

How may 1/8th" ball-bearings does it take to fill Paris Hilton's belly-button?
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Old 12-20-09, 03:24 PM
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Originally Posted by HillRider View Post
Removal requires removing the drive side cartridge FIRST. Then remove the plastic nds cup. Do not try to remove the plastic cup first.
I didn't know that, buggered up a number of them. Thanks for the tip HillRider (as usual)!!
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Old 12-20-09, 03:37 PM
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Originally Posted by operator View Post
...Not sure why any of this is surprising to anyone.
He is soooooo smart, I am glad he's here to tell us how dumb we are
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Old 12-20-09, 04:30 PM
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Originally Posted by Mr IGH View Post
He is soooooo smart, I am glad he's here to tell us how dumb we are
Mr IGH:

Ops
is not playing self ego-stroking games. He actually is extremely intelligent in all things bicycle. And he is aware that his attitude needs a bit of work. You should have seen him a year, or more, back. He is much more easy-going at present. So I guess it's a trade-off: In exchange for a near photographic-memory of his experience with working on bicycles as a profession, he had to adopt a method of being as diplomatic as a flame-thrower.

Advice: Ignore the attitude. And use Ops as a resource of knowledge. He has the equivalent of the Encyclopedia Britannica (Aardvark - Zygote) of bicycles in his upstairs.

Cheers!
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Old 12-21-09, 09:09 AM
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Originally Posted by Panthers007 View Post
Mr IGH:

Ops is not playing self ego-stroking games...
1.) He didn't actully help anyone in this thread. The good advice came from others, OP chimed in that we're all stupid for not knowing this technique. If he actully knew the procedure, why didn't he post it?

2.) His attack on my answer is wrong. Shimano changed to plastic for the reason I mention. I posted:

IMHO, the plastic is better because it gives/flexes and allows the UN54 to work fine even if the frame's bb isn't faced perfectly.
Operator refutes my post with exaggaeration and misquotes:
You just made this up.

The plastic cup doesn't handle extremely bad shell facing (because that's what it takes to really cause a problem) than the lipless metal cup.
Notice how I said, "(less than) perfectly" and he came back with "extremely bad". Also, if I'm wrong, why is the plastic cup deformed so badly it can't be extracted directly? Poor Operator, so sure of himself and yet most of the time has nothing to add to the thread. What's his contribution here other than negative BS? He certainly didn't help the OP....
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Old 12-21-09, 01:21 PM
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Operator clearly has no idea that IMHO means IN MY HUMBLE OPINION because he wouldn't of said "you just made that up" as a reply.

Really? Its not really his opinion?? Really? He lied about what his opinion was?

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Old 12-21-09, 01:29 PM
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Originally Posted by Panthers007 View Post
How may 1/8th" ball-bearings does it take to fill Paris Hilton's belly-button?
80.
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Old 12-21-09, 01:46 PM
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Originally Posted by Panthers007 View Post
Mr IGH:

Ops
is not playing self ego-stroking games. He actually is extremely intelligent in all things bicycle.
Based on some of the things I've seen operator type, I'd rate him as above average, not extremely intelligent in all things bicycle.

His bias towards certain systems (dual-control road levers, for instance), makes him blind to the fact that one system ain't the best for EVERYONE.
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Old 12-21-09, 04:13 PM
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My actual message stands: Get used to it! The worst thing to do when someone ticks you off - is to emulate them. So, gentlemen & ladies, may we chill and move forward?

Thank you.
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