What model is what on square taper bb's??
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PopsTrippin
Marin Fan
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Not sure what model corresponds with which groupset but I'd say working down from the best (XTR)
Shimano cartrigde bottom brackets are typically coded with a model designation and two numbers: shell width and length.
•Model designations include:
◦Square Taper: CT21, LP27, UN40, UN51, UN52, UN71, UN72, UN91. These are all interchangeable if the other numbers match. Listed in order of quality, CT21 is worst, UN91 is best.
Shimano cartrigde bottom brackets are typically coded with a model designation and two numbers: shell width and length.
•Model designations include:
◦Square Taper: CT21, LP27, UN40, UN51, UN52, UN71, UN72, UN91. These are all interchangeable if the other numbers match. Listed in order of quality, CT21 is worst, UN91 is best.
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UN90/91 is M900 XTR level. The lightest and best they made, but no longer 
.
UN7x is XT level, no longer made
UN50/1/2/3 is your LX/DX/STX-ish level these are no longer made
the x increment is just production changes.
.. then UN54 was introduced when they stopped the rest.
It is actually half way between UN7x and UN5x, middle of them both for weight and quality is good, like UN7x's from what I've seen.
There is now a UN55 as well, I guess a revision on the UN54.
But ignore the none UNxx series, no point in them when UN54/55 are about £15.
Well that approximately right.
.UN7x is XT level, no longer made
UN50/1/2/3 is your LX/DX/STX-ish level these are no longer made
the x increment is just production changes.
.. then UN54 was introduced when they stopped the rest.
It is actually half way between UN7x and UN5x, middle of them both for weight and quality is good, like UN7x's from what I've seen.
There is now a UN55 as well, I guess a revision on the UN54.
But ignore the none UNxx series, no point in them when UN54/55 are about £15.
Well that approximately right.
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rojo":10zd7p25 said:Thanks for that guys
So they don't make Xt or xtr anymore seems a shame.
Mainly because XTR hadn't used one for ~15 years
XT & LX hasn't for ~ 12 year
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The UN54 and now UN55 fill the gap left though and I guess must sell pretty fine especially at the price they are going for, which in the current very high prices for Shimano good compared to a few years ago, they are a bargain.
They are hollow spindles, hence the drop in weight from the other UN5x series of old.
But with mass production, cost cutting measure by not having quite the chrome finish as UN7x series.
I think many people here use them all the time.
If anyone knows what changed between UN54 and the new UN55 that's just been released, I'd like to know ?
They are hollow spindles, hence the drop in weight from the other UN5x series of old.
But with mass production, cost cutting measure by not having quite the chrome finish as UN7x series.
I think many people here use them all the time.
If anyone knows what changed between UN54 and the new UN55 that's just been released, I'd like to know ?
nutcase-retro
Retro Guru
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UN55
After reading all the above posts. I went on Ebay to checkout UN55 b/b, they are being listed as road b/b. Looks as if they are the same quality, 54 is mtb and 55 the road version.
After reading all the above posts. I went on Ebay to checkout UN55 b/b, they are being listed as road b/b. Looks as if they are the same quality, 54 is mtb and 55 the road version.
