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  • Shimano UN55 Square Taper Bottom Bracket
  • Shimano UN55 Square Taper Bottom Bracket
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Select  Colour
Select  Option
English Thread
Italian Thread
Select  Size
73 x 110mm
73 x 118mm
70 x 107mm
70 x 110mm
70 x 113mm
70 x 115mm
68 x 110mm
73 x 107mm
73 x 113mm
73 x 122.5mm
68 x 118mm
68 x 115mm
68 x 127mm
68 x 122.5mm
68 x 107mm
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Shimano UN55 Bottom Bracket

Shimano Road UN55 model has super-accurate bearings for smooth operation and improved durability.

Features:

  • Durable, hard-wearing sealed cartridge bottom bracket.
  • Maintenance-free sealed cartridge bearing assembly keeps out dirt, mud and water for long bearing life
  • Fast and easy installation without adjustment
  • Hollow Spindle
  • Narrow body allows clearance for cable routing under the bottom bracket

Buy Shimano Components from Chain Reaction Cycles, the World’s Largest Online Bike Store.

  • Colour: Silver
  • Size: 73 x 110mm, 73 x 113mm, 73 x 118mm, 73 x 122.5mm, 70 x 107mm, 70 x 110mm, 70 x 113mm, 70 x 115mm, 68 x 110mm, 68 x 118mm, 68 x 115mm, 68 x 127mm, 68 x 122.5mm, 73 x 107mm, 68 x 107mm
  • Option: English Thread, Italian Thread
 
Rated 4.7 out of 5 by 47 reviewers.
Rated 4 out of 5 by il prodotto e di buona qualita prodotto con qualita - prezzo ottima, lo consiglio per chi vuole spendere poco ed avere buone prestazioni 18 October 2014
Rated 4 out of 5 by Great value BB - good solid build - reliable I bought to replace my last one with 2 years and about 5000 miles use. Only reason it needed replacing was because I was too keen with the degreaser and stripped the grease out the bearings. 28 September 2014
Rated 5 out of 5 by Does what it's supposed to Simple, no fuss BB for your average rider. Smooth, simple to fit and does the job. Works for a gajillion miles, and cheap enough that even if it didn't replacing it is hardly a painful experience. What more could you want? 27 September 2014
Rated 5 out of 5 by Shimano quality, good price. Fitted without any pain, seems to be doing it's job nicely. Only minor niggle is that the non drive side has a collar on it and the ten plus year old BB I removed did not (sat entirely within shell). This led to me using some sealant to prevent dirt being able to get in the gap. 20 September 2014
Rated 5 out of 5 by simple quality as it says above, simple, quality item cheap enough to keep relacing 15 September 2014
Rated 5 out of 5 by Cheap and good I think it's one of the best standard (affordable priced) JIS/square taper Bb in the market. Fit one on my hybrid frame (73mm shell width) and the other on my touring/CX frame (68mm width) and both rolls smooth like butter. Put on some grease on the taper to install the crank arms, and then tighten the bolts all the way to prevent creaking. Shimano quality!! 13 September 2014
Rated 5 out of 5 by Good B/B for the money Good reliable square taper B/B, seems to run smooth enough for me as i have put a couple thousand miles on mine already, i have bought another 2 'cos the price at the mo, well you can't go wrong, i would recommend this B/B to anyone looking. Only niggle, could have a zinc plated spindle for weather protection. 31 August 2014
Rated 5 out of 5 by Shimano Product, High Quality, Very sturdy. Very well made. Drivers side thread is Steel and other side i alloy, be very carefull when screwing in and remember to put soem grease in . Good Quality product . 25 August 2014
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31 Questions : 58 Answers

Product Q&A

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3 answers

Does this come with crank bolts?

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9 months ago
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Answer: 
Crank bolts are not included with this bottom bracket; the suggested bolts below are compatible.
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9 months ago
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Answer: 
Yes comes with plain hex head steel ones
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7 months ago
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Answer: 
No, no crank bolts comprised.
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7 months ago
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What size UN55 bottom bracket to use with a Giant Defy 3 2009 model please?
Using a triple crankset as standard spec for that model bike.
1 year, 1 month ago
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Answer: 
We do not have specific technical data for the Giant Defy to identify the size of bottom bracket you need. Though it is easy to identify the size you need your self.

You will have to measure your frames bottom bracket shell width, most likely 68mm. Then remove your crank arms and measure the current bottom bracket spindle length. With these two figures you can select the appropriately sized UN55 BB.

For removing and fitting a BB at home you will need the tools below.
1 year ago
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Answer: 
It al depends on your set up- depending on your frame, crankset and set up the axle comes in different lengths.

The best way is to replace old and copy it.
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2 answers

Choosing correct bottom Bracket

Which size and version replaces a VP-BC55 with a 113 mm Spindle and 38mm housing diameter?
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1 year ago
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Answer: 
From what i can see the version you need is the English 68 x 113mm version. You can check this by measuring the with of the bottom bracket shell on your frame. This will give you the first measurement you need. (ie. 68,70) the next thing to do is measure the old bottom bracket from end to end.(spindle end to spindle end) This will give you the second measurement. (ie. 113, 115 etc) If you have any further questions please contact us at tech@chainreactioncycels.com
1 year ago
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Answer: 
It will be 113mm axle.
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11 months ago
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Answer: 
The axle length required is dictated by the chainset you are using, as different chainsets will have differing levels of offset. If you are only replacing the bottom bracket on an existing crank, side with the longer option if stuck between two sizes.
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11 months ago
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Answer: 
For either choice you will be gaining about 1mm either side of your drivetrain which makes hardly any difference to your chainline. Go for whichever you like- they will both work but if I was you I would go for shorter a tad as a rule of thumb.
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I have a Canondale T700 frame circa 1994. The shell is 68mm wide with a diameter of 30mm.
I don't have the original bottom bracket to measure
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11 months ago
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Answer: 
For a triple chainset it is recommend that a 118mm or 115mm spindle is fitted.
11 months ago
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Answer: 
It is hard to tell without knowing your previous axle length. It is a case of trying unfortunately. I would go for 116mm first and take it from there. Put it in- measure your chainline and amend (buy another one) where necessary. You could also look on forum- try finding someone who has the same bike and knows the axle length.
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Dea Sir./M.am.
I need to replace my BTwin Riverside-5 bottom-bracket. I bought it on 2009, I use it every day for commuting to work and it has about 14000km. I want to buy the new one and then disassemble and replace mine, so that I can keep using my bike.
The bottom bracket is a Shimano Square Taper.
I measured the diameter of the left side "screw", and it is about 35 mm. While the distance between the pedals is about 140mm.
Can you suggest the correct bottom bracket dimensions to use to replace mine.

Thank you in advance for your help.

Best Regards,
Simone
10 months ago
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Answer: 
The description of BTwin Riverside-5 2009 says it has octalink Shimano M521, 48-36-26 crankset with 121cm-length BB. Octalink, not square.
May be you have some another type of this bicycle, so try to find the type of your crankset. BB depends only from crankset, not frame of the bicycle.
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Answer: 
Hi Simone,
its the axle length that you need to measure, this requires removing the crank arms from the bottom bracket then measuring the axle with something suitable , ie vernier calipers, next step is to measure the bottom bracket shell width,,
bb shell x axle width is the one youll need to fit
ie 68 x 110mm hope this helped

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Answer: 
The required Bottom Bracket size specified by Shimano is 68x113mm.

As this size is not currently availabe for the UN55, the suggested cartridge below will be a good alternative.
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Answer: 
Hi I'm not sure as I haven't heard of the bike but will try and help.First of if it's tripe crank you need a 118mm in length,also is this a road bike or a Mountain Bike,a UN55 will fit road and mountain bike but depends on what crankset your using if Square taper then this will work and if it's two piece you will need a Shorter 1 in length.
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Answer: 
The suggested square taper tool suggested below is required for fitting this bottom bracket. For future reference; the crank puller will likely be required to dissemble it again.
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Answer: 
This is perfect:
http://www.chainreactioncycles.com/it/it/weldtite-shimano-bottom-bracket-cartridge-tool/rp-prod86711
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Answer: 
I believe the Cube LTD Race ran a 68mm bottom bracket shell; the length of axle you need will depend upon the model of crank that you intend to fit. The recommended axle length for square taper cranks can often be found on the paperwork for them.
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Answer: 
Hi if your using a MTB and your putting a Triple crank on you need a 68 by 118mm.
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I’ve been using UN54’s (68 x 122mm British Thread) for a number of years, they now appear to be either discontinued or out of stock. Is a UN55 (68 x 122.5mm British Thread) a compatible replacement? If so what actually is the difference as they appear to be identical

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Answer: 
The UN55 is perfectly compatible as a replacement for the UN54 - forget about the 0.5mm numeric difference! I think the UN55's left cup washer was slightly redesigned (different shape and, I think, different material) to eliminate some creaking that the UN54 could suffer from.
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Answer: 
The difference is the axle length and bearings. The axle will be ok with only 5 mm difference. The bearings- you will never notice the difference.
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