Product ID: 333222382816

Shimano
UN55 Square Taper Bottom Bracket

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Found: 05-17-17
Expires: 07-28-17

all about the

Shimano UN55 Square Taper Bottom Bracket

The Shimano BB-UN55 bottom bracket is one of the most popular choices for touring and mountain bikes using a square taper crank. It's simplicity and durability means easy servicing, and long life. The UN55 is available in a number of sizes, and features sealed cartridge bearings for long life and all-weather reliability.
  • Hollow spindle
  • Available in 68mm English, 73mm English, and 70mm Italian shell widths
  • Available in 107mm, 110mm, 113mm, 115mm, 118mm, 122.5mm, and 127mm spindle lengths
  • 25% more durable than previous UN54 model
  • Crank bolts not included
questions about the

Shimano UN55 Square Taper Bottom Bracket

asked by: A Visitor
Will the un-55 fit a 1978 schwinn competition scrambler bmx bike.Sugino super maxy cranks
answered by: kristenkey
If the crank uses a JIS squared tapered bottom bracket, than it will work. If you're local, bring the bike by and we'd be more than happy to take a look!

Thanks!
asked by: A Visitor
Can i run this with the White industries eno crankset
answered by: canteau
Yes, the White Industries ENO crank uses a JIS square taper bottom bracket.
asked by: A Visitor
Just got a bike with a BB-UN55 70 X 116. What cranks fit that Bottom Bracket?
thanks
answered by: canteau
You will need to find a crank that works with the rest of the drivetrain (proper number of chainrings, proper chainring sizes and chain size) once you find the crank that checks all of those boxes you will need to get an Italian threaded bottom bracket with a spindle that meets the needs of that crank.

116mm spindles are used on some track and road double cranks that require a JIS square tapered crank.
asked by: A Visitor
I want to use a 127mm. What Derailleur will work with this extra width? Mtn or Road is ok
answered by: canteau
The front derailleur is determined by the style of the crank, size of the chainrings and shifter, not the bottom bracket width.
asked by: mic...@gm....com
Hi Which of these BB length for Sugino XD 600 crank (triple) on Surly LHT? thanks
answered by: canteau
Sugino recommends that you use a 110mm spindle with road front derailleurs and 113mm spindles for mountain front derailleurs.
asked by: A Visitor
What size are the crank fixing bolts? length, diameter and thread?
answered by: canteau
These Problem Solvers bolts should work with most cranks: http://www.treefortbikes.com/product/333222342814/1213/Problem-Solvers-8mm-Hex.html
asked by: A Visitor
Can this one replace my VP-BC-73T? Its for my Specialized Rockhopper (2015)
answered by: mwirth
Yes it can. This is the Shimano version of the VP-BC-73T. Thanks!
asked by: A Visitor
What size for Shimano triple Alivio 70mm shell x 107.8mm
answered by: t.young
70x107 should work as long as you're sure the frame is Italian threaded.
asked by: A Visitor
Can bb un55 68x122.5mm use with fc-m391
answered by: t.young
From what I can see, that should work fine.
asked by: A Visitor
M737 crankset; trying to set up as 1x8 pub cruiser. What length spindle recommended?
answered by: t.young
107 for 68mm shell and 113 for 73mm shell is what's recommended, from what I can see.
asked by: perri
Would the UN55 Shimano BB 68 x 110 be able to replace a RPM BB7420 68 x 110.5?
answered by: t.young
You should be fine, I doubt that half-millimeter difference will affect anything.
asked by: freeflight
Original BB is UN-54 68/118. Can the UN-55 68/118 be used to replace it.
answered by: t.young
The shell width and spindle length is the same, so there shouldn't be a problem.
asked by: A Visitor
What is the difference between a UN55 and a UN26 Shimano Bottom Bracket?
answered by: t.young
The un-26 has a plastic cup on the (I believe) non drive side and alloy on the drive side while the un-55 has alloy cups on both sides.
asked by: ajkovacs
For a 73mm x 122.5mm BB, How does a UN26 and a UN55 compare in weight?
answered by: mlewis
Shimano doesn't list weights for either of these bottom brackets, so we don't have a good basis for comparison.
asked by: A Visitor
Would this the replace a SE 3-pc Cr-Mo, 48 Spline Sealed Euro, 46T Alloy.
answered by: mlewis
We can't find any specific info on the crank you're referring to, you may need to take it to a local shop for further identification.
asked by: tnelson32
What spindle length to use for cross frame w 68mm english bb shell & old xt triple crank??
answered by: mlewis
Yes, chainline is measured from the center of the BB shell, there's some great info about chainline at sheldonbrown.com/chainline.html
answered by: tnelson32
Thanks!, Is 43.5mm chainline you mentioned measured from mid-point of bb shell?
answered by: canteau
Square taper XT cranks were made to be used with bottom bracket spindles from 113-122.5mm in length depending on the chainline required.

With a 9-speed cassette the middle gear on the back should line up with the middle chainring.

If the frame is using a 130mm rear road hub and a 43.5mm chainline, I would start with something in the 113mm range and go from there.
asked by: Edi2113
Would this be good for a Miche Advanced crankset?
answered by: canteau
It will work, but won't be ideal, the Miche uses an ISO (Campagnolo) taper and Shimano bottom brackets are JIS (Japanese International Standard). You can interchange the 2 but the chainline won't be right.
asked by: A Visitor
Can this replace a UN26 68x122.5 from an Acera FC-M391 triple crankset?
answered by: mlewis
Yes, this would be the appropriate replacement for that crankset, just select the appropriate size from the drop down menu.
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reviews of the

Shimano UN55 Square Taper Bottom Bracket

Just The Dirt
positive starpositive starpositive starpositive starpositive star
4.8 GEARS
4 reviews
LIKES
Durable (2)
Good Quality (1)
DISLIKES
WORKS FOR
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5
GEARS
reviewed by:
Review of the Shimano UN55 Square Taper Bottom Bracket:
Replaced a dead bracket on a 2012 Diamomdback overdrive fantastic, now works like brand new.

Yes, I would recomend this to a friend.

Likes: Durable, Good Quality

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5
GEARS
reviewed by:
Review of the Shimano UN55 Square Taper Bottom Bracket:
Used it in a 1991 Trek 700 and loved the sealed cartridge arrangement. Even if water or dirt finds their way into the BB housing, the bearings are not affected. Installation also is very easy - no chance to tighten it up too much, as you only have to install with the correct torque and it is all set - no adjustments needed.

Yes, I would recomend this to a friend.

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5
GEARS
reviewed by:
Review of the Shimano UN55 Square Taper Bottom Bracket:
The Shimano UN55 is reliable, cost effective, and easy to replace. The UN55 cartridge bearing is readily available in a myriad of sizes.

My original bottom bracket bearing was a different manufacture and it failed sooner than it should. Nothing worst than a hitch at 12 o'clock or a annoying squeak.

Yes, I would recomend this to a friend.

Likes: Durable

member review badge
positive starpositive starpositive starpositive starpositive star
4
GEARS
reviewed by:
Review of the Shimano UN55 Square Taper Bottom Bracket:
Basic bottom bracket used to replace an older non-sealed unit on a vintage bike. I didn't much like the plastic non drive side bushing, but it seems to work well. I put 2k miles on it so far and no issues. The bike is a gravel grinder and used on some pretty muddy trails; the sealed bearings cut down on maintenance issues.

Yes, I would recomend this to a friend.

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specs for the

Shimano UN55 Square Taper Bottom Bracket

Spindle Length (mm):  
113, 118, 115, 110, 122.5, 107, 127
Spindle Interface Type:  
Square Taper - JIS
Bottom Bracket Shell Width:  
68mm, 70mm, 73mm
Bottom Bracket/Frame Interface:  
English, Italian
 

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