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Shimano BB-UN54 Bottom Bracket, 68 X 107mm

4.4 out of 5 stars 31 customer reviews

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  • Shimano UN54 68 x 107mm Bottom Bracket
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Technical Details


Product Description

Shimano UN54 Square taper bottom brackets.
  • Hollow spindle
Item Specifications
Weight313g
BB Thread TypeEnglish
Spindle Interface TypeSquare Taper JIS
Spindle Length107mm
BB Shell Width68mm

Product Details

  • Shipping Weight: 12 ounces
  • Domestic Shipping: Item can be shipped within U.S.
  • International Shipping: This item is not eligible for international shipping. Learn More
  • ASIN: B001M9KGBG
  • Item model number: EBBUN54B07
  • Average Customer Review: 4.4 out of 5 stars  See all reviews (31 customer reviews)
  • Amazon Best Sellers Rank: #508,319 in Sports & Outdoors (See Top 100 in Sports & Outdoors)
  • Product Warranty: For warranty information about this product, please click here

Customer Questions & Answers

Customer Reviews

Top Customer Reviews

Size: 68 X 118mm Verified Purchase
My bottom bracket was wearing out fast. There was lots of "play" in the crank, and when I pedaled hard, it felt sloppy and made a clunky noise. I took my bike to a shop to have the bottom bracket repaired. They must have taken it out and worked on it, but I suspect the original was not a sealed bracket. They did a nice "tune up" of everything else, but only tightened the bottom bracket instead of replacing it. I didn't realize this until I got home and rode it. It was not good enough.

So I decided to do it right. You need an extractor to remove the pedal arms. (It's a kind of gear-puller.) You also need a special socket to loosen up the old bracket, and maybe a good pair of channel locks or vice grips, depending on what's holding it all together. On my bike, I had to turn BOTH SIDES FORWARD to loosen the bracket. (I learned this the hard way.) It rides like new now. I even replaced the bottom bracket on my step-daughter's bike. Remember to tie the bike off the ground, right side up (to some garage rafters, maybe) in order to make it easy to work on. You'll need to measure the overall length of the bracket, to the outer edges of the square ends of the shaft, and the inner length of the cylinder, to get the right part. Make sure you get the right one. Ask a bike expert if you need some help. I did!

As an Amazon affiliate myself ([...]; My AMAZON Site, My STORES) I'd recommend this product.
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Verified Purchase
I rebuilt a Trek 800 for a friend (it had some serious problems!) and used this BB to replace the stock one (I don't know what you call the style, but it was a square taper). The UN54 fit great! I used the 122.5 which i believe was the stock size. However, one tooth of the inside ring hit the frame. The wear on the frame, however, leads me to believe that it was lightly knocking on the frame all along. However, the chainrings are the long-discontinued Shimano Biopace-- if you know them, you can imagine why only one tooth would hit the frame.

ANYWAY! This otherwise fit perfectly. It was a tremendous upgrade from the long-worn BB. Along with a few other affordable upgrades, this trek 800 is a nice little commuter. I'm probably going to throw one in the Trek 3500 I built up last summer. It squeals and that annoys me. I look forward to replacing it. If you're a harder core rider, heavier, etc, you might consider replacing the plastic non-drive-side cup with an aluminum one (you can buy them online-- just search). They're about as much as this BB, so if you think you can tolerate the plastic, it shouldn't bug you.
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Size: 68 X 122mm Verified Purchase
This cartridge bottom bracket is the now-standard replacement for loose-ball bearing bottom brackets. For square-taper cranks. Easy to install. Note that one of the threads is left-handed, and many torque wrenches do not "click" in reverse. Size is by thread diameter and length of crank axle.
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These are very good sealed cartridges which are easy to install, make pedaling your bike easier and have a long service life. It is important to get the correct width of spindle (that's the axle used to attach the crank arms, visible in the picture), for example they come in 110mm, 113mm or maybe 115mm widths and more. Just measure the current spindle width on your bike to get the correct or close size. This cartridge displayed here has the standard square tapered spindle which is usable on most bikes especially lower to mid range priced bikes. Some people do not like the plastic threaded bushing which comes with the cartridge, but be careful how you install and it will probably be fine, i have never had a problem with these. The way i install these, a method which has worked for me, is to put the plastic bushing in first all the way until it is seated, then install the cartridge, but do not tighten real tight, if there is still a little gap between the steel cartridge flange and the bottom bracket housing, back out the cartridge a lot, then back out the plastic bushing maybe 1/4 to 1/2 turn (counter clockwise) and re-install the cartridge and check to see if it is seated, (which it most likely will be) and if not seated, repeat the process with another 1/4 to 1/2 turn to the plastic bushing and you should now have enough clearance for the steel cartridge to seat. (The cartridge steel flange will be flush with the BB Housing). The way i install these cartridges just makes a nice neat job, that's all. If you install the steel cartridge first, and have it seated flush with the BB housing, and then install the plastic bushing last, that's where people bust the plastic bushing or maybe strip the threads and get mad at the plastic bushing, etc. My way is much better. ~gg
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Used the 68-118 to replace a 68-117 cartridge, so it did stick out slightly more than the original, but works well enough. Noticed that some people prefer these to the older style bottom brackets with the adjustable cones and ball bearings. Call me old fashion, but I prefer being able to simply take apart the bottom bracket, clean-out the parts, re-grease, put back together, adjust and go, rather than having to go shopping for a whole new part every time.
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By A. Gabriele on September 21, 2011
Verified Purchase
Replaced the original cup-and-ball bearings (two outer races, a bunch of balls, the crank shaft, grease...) in my 25 year old Canondale SM600 (mountain bike) just like that. Wonderful. Don't forget the special tool. Use a torque wrench: 50-70 Newton Meters, about 45 Ft.Lb. Don't skip the grease or anti-seize compound. Chainwheel side is left hand thread. Two crank bolts are included.

Update: When I installed it, I did not use spacers on the chain side causing the chain ring to be about 1/8 inch inboard of it's original location, (the original crankshaft was asymmetric), I noticed but did not think it important .... wrong .... so I got some spacers for it and reinstalled (and used a new cup). The front derailleur, it turns out, is very sensitive to this , at least on this bike, and I could not get it adjusted for good function.
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