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Author Topic: Bottom Brackets?  (Read 5300 times)

simulatedjim

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Bottom Brackets?
« on: February 08, 2014, 03:52:13 pm »
I bought a Beast frame and fork, it is the Extreme Series.  The factory Bottom Bracket is Shimano BB-UN52, 110 mm spindle.  I've been reading about what the numbers mean but can't find this exact number to buy.  Does the "52" mean better quality? The higher this number the better? Will a BB-UN55 110mm work? 

w2zero

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Re: Bottom Brackets?
« Reply #1 on: February 08, 2014, 09:10:17 pm »
I have been meaning to look up some BB stuff.  Maybe this link will be of service to you.  http://sheldonbrown.com/bbsize.html
855
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simulatedjim

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Re: Bottom Brackets?
« Reply #2 on: February 09, 2014, 04:55:26 am »
Yes I found his site and it shows compatibility with some but skips over others which is what confused me.
CT21, LP27, UN40, UN51, UN52, UN71, UN72, UN91. the list shows these are compatible but the "55" is isn't? Trying to understand what the numbers mean.

Scooter

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Re: Bottom Brackets?
« Reply #3 on: February 09, 2014, 10:10:21 am »
I believe the 55 has an aluminum adapter and the 52 has a plastic adapter.
957?
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Colin

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Re: Bottom Brackets?
« Reply #4 on: February 10, 2014, 09:49:35 am »
Pretty sure the 55 is just a Quality/Year indicator.

higher first digit = better quality/lower weight

That's all I treat it as, anyone disagree?

Col.
« Last Edit: February 18, 2014, 04:33:19 am by Colin »
2001 OzM
2000 OzX
1999 x500
1999 900 Frame
1998 4000se
1998 4000
1997 957 Frame
1997 857 Frames
1997 XP-X (856)
1995/6 x55/x56 Frame
1992 962 Frame
1991 Marin Pine Mountain with a Flex Stem

Neffro

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Re: Bottom Brackets?
« Reply #5 on: February 17, 2014, 03:34:25 am »
In my experience the higher the two digit number, the higher the quality. I have only used UN-XX as replacements and the are all decent, but the higher end ones weigh less. I am not sure how the bearings differ (or if they do). I think the 70's were equated to XT level and the 90's to XTR.

I do know that the low end LP-XX can be junk right out of the box. Some feel like there is sand in them when they're brand new and they weight as much as a small boat anchor.
When all is said and done, more is said than done.

simulatedjim

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Re: Bottom Brackets?
« Reply #6 on: March 29, 2014, 03:56:34 pm »
Everything I can find, agrees with what is stated above.  I got a UN-54 and it has a plastic half and the UN-55 has aluminum on both sides.(higher number)better parts.