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23 votes
Accepted

Is it correct that the bottom bracket shell thread does not go all the way around?

Are you referring to the absence of material at the chainstay openings in the bottom-bracket shell? This is absolutely normal. This is what a BB shell looks like before being built into a bike: ...
Adam Rice's user avatar
  • 30.1k
22 votes

Drive side part of bottom bracket is impossible to remove and has destroyed tool fitting

Unless your frame is Italian, or a handful of unlikely other makes, your bottom bracket is left-threaded on the drive side. https://www.parktool.com/blog/repair-help/bottom-bracket-removal-...
whatsisname's user avatar
  • 12.1k
20 votes
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Difference between Road/Mountain Hollowtech II Bottom Brackets?

I'm going to limit this answer to Shimano Hollowtech II BBs as per the question. Some other brands do it a little differently. Mountain external bearing crank spindles are longer than road spindles, ...
Nathan Knutson's user avatar
19 votes
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Should square taper cranks be greased before installation?

I started getting seriously into bike work circa 2002 and was lucky enough to come across Jobst Brandt's view of the topic around that time. Since then, most of which time I've spent working as a ...
Nathan Knutson's user avatar
18 votes
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What tool should I be using on this bottom bracket?

The proper tool to interface with that bottom bracket is one like this: The pictured tool is a Park HCW-18 and runs about $15 USD. There should also be a large nut that threads on top of the bottom ...
Ted Hohl's user avatar
  • 6,377
15 votes

How can I tell the difference between a J.I.S. and ISO square taper bottom bracket?

The width across the narrowest part of the flats (end of spindle): JIS = 12.65mm ISO = 12.33mm Use calipers.
Pedalphile's user avatar
15 votes

How can I remove the stripped plastic cups of a bottom bracket?

FAG bottom brackets (BB) with plastic mounting rings are very common in Germany. The cartridge bottom bracket is really good and resilient, however the polyamide (PA) mounting rings are horrible. As ...
gschenk's user avatar
  • 9,778
15 votes
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What type of crank fitting is this?

The bottom bracket spindle is for cottered crank. The bottom bracket looks like threaded one, so it is likely that it can be replaced with square taper or external cup bottom bracket. To tell which ...
ojs's user avatar
  • 22.1k
15 votes
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Broken bottom bracket?

The bottom bracket is not damaged, the left hand crank arm is. You have a 'two piece' crank where the right side crank is permanently attached to a steel axle, and the left hand crank clamps onto the ...
Argenti Apparatus's user avatar
11 votes
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Replace old square taper bottom bracket / ISO or JIS?

First, very nice drawings and measurements. This makes answering easy. According to the Sheldon Brown link, for JIS "The standard width across the flats at the end of the axle is 12.65 mm", which is ...
ojs's user avatar
  • 22.1k
11 votes
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Struggling with bottom bracket installation

Threadless cartridge BBs have their place, and that place is where the threads are destroyed. Thankfully you're not there yet. They are a compromise because they tend to have creak issues sooner or ...
Nathan Knutson's user avatar
11 votes

Pedals turn but bike doesn't move

Judging from your videos, it appears that the chainrings and crank are no longer connected. It appears that you have something called a one-piece crankset. If you are confident that you can learn how ...
MaplePanda's user avatar
  • 15.6k
11 votes
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Are the chainrings supposed to have irregular sized teeth?

Yes, modern chainrings have teeth that vary from each other. They are formed that way to enhance shifting between the different chainrings. Older chainrings from a couple of decades ago had teeth ...
Ted Hohl's user avatar
  • 6,377
10 votes

Disassembling crank on a 2006 Trek Pilot 2.1

I had this exact issue come up at work today, with the same crank. It was quite frustrating! Unlike the OP, I tried progressively harder hammer smacks early on. And also unlike the OP, I was unable ...
Nathan Knutson's user avatar
10 votes
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Bottom bracket too tight to screw in by hand

If one side screws in without problems, and you've verified the thread orientation, then it's not a compatibility problem. ( http://sheldonbrown.com/bbsize.html - scroll down to "bottom bracket ...
Mike Baranczak's user avatar
10 votes
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What type of bottom bracket does my bike have?

There's nothing integrated there - instead, there is one cup still in the frame, and it has been painted red at some point. You'll need either a careful hand with a large spanner to remove it, or to ...
Criggie's user avatar
  • 125k
10 votes

What kind of tool do I need to change my bottom bracket?

You have a traditional cup and cone BB. You need a lockring wrench to undo the locknut, such as ParkTool HCW-5, but many other exist. Then you will need a bottom bracket wrench, such as HCW-4, to get ...
Vladimir F Героям слава's user avatar
10 votes
Accepted

What is this bottom bracket tool called?

That is a pin spanner. The photographs and product listing were made by someone who doesn't know about bikes. You never put it on sprocket or gear teeth. Also, to know the tool you're buying is useful ...
Nathan Knutson's user avatar
9 votes
Accepted

Are the Truvativ powerspline BBs reliable?

The TruVative power spline BB is a decent, if inexpensive design, and is unlikely to have failed through a design fault. All bikes, regardless of price or quality level, require periodic maintenance....
zenbike's user avatar
  • 29.8k
9 votes
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The bolt of my pedal's crank arm broke, what could be the causes?

The "bolt" that broke is not a part of the crank. Your bike has a so-called square-taper bottom bracket and one side of the axle broke off. This axle is a solid metal part that runs from one crank arm ...
StefanS's user avatar
  • 368
9 votes
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Ideal distance between chainring and chain stay

4mm at the closest point is about the safe spot. 3mm is about the sane bare minimum you can go to if you want to push things. Less is asking for trouble. Note that frames, cranks, rings, and spindles ...
Nathan Knutson's user avatar
9 votes

Why were press fit bottom brackets invented?

Carbon is the dominant frame material in performance bicycles. You can't thread carbon. There are two ways to get bottom bracket cups into a carbon frame: bond (industrial-strength glue) an alloy ...
Weiwen Ng's user avatar
  • 32.6k
9 votes

Drive side part of bottom bracket is impossible to remove and has destroyed tool fitting

The drive side was probably installed without anti-seize/grease, and has corroded to the frame. Presumably you want to save the frame and replace the cartridge. Starting with oils is a good first ...
Criggie's user avatar
  • 125k
9 votes
Accepted

I replaced my bottom bracket and now my crank arm bottoms out on the square shaft before it can be torqued. What did I do wrong?

Of note is that the amount of gap you have before the chainring bottoms out on the old cup is itself unusually close. That's fine if it works, but it helps to explain what's going on here. There is ...
Nathan Knutson's user avatar
9 votes
Accepted

How should I remove this crankset?

The issue seems to be that what is considered "universal" changes over time. The OP seems to have a crank puller that is universal for square-taper bottom brackets. The photo looks like a ...
Armand's user avatar
  • 2,835
9 votes

Searching for a Pressfit BB replacement for my road bike

You've got a BB386 shell and Shimano road cranks, which are all 24mm. There are a lot of individual replacement bottom bracket models that could do what you need here. The expensive ones are often ...
Nathan Knutson's user avatar
9 votes
Accepted

FSA "24 mm" crank stuck in Shimano "24 mm" BB

Yes, the problem exists. For some unknown reason, some of FSA’s “24mm” spindles are actually 24.07mm in diameter. Hence, they don’t fit well into Shimano’s 24.00mm system. You need the correct FSA BB ...
MaplePanda's user avatar
  • 15.6k
9 votes
Accepted

Loose bottom bracket on MTB

It looks like your BB cartridge is no longer pressed into the frame shell. When you removed the cranks did it just sort of fall apart? That is a signal that for whatever reason the BB is worn so that ...
Warren Burton's user avatar
9 votes

How can I measure whether pedals and bottom bracket are properly aligned to each other and parallel?

The big issue with the test you're doing is that misalignment of this type, resulting in the warbly pedal feeling, can be either in the pedal spindle, the crank, or the BB spindle, and if all you're ...
Nathan Knutson's user avatar
8 votes
Accepted

Getting the right Bottom Bracket

If you have an idea of what model of frame it is, it would help. Otherwise, your best bet is to take it to a bike shop and try an ISO bottom bracket (gently) to see if it fits, or measure the threads ...
Batman's user avatar
  • 46.2k

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