Some basic BB knowledge please
10-16-12, 07:09 AM
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Some basic BB knowledge please
It's been a while since I've delved into bicycle mechanics and specs. In my day you only seemed to need to know the threading (English, Italian) and you pretty much knew your stuff. I'm seeing the term BB30 thrown around a lot and was wondering if someone could school me in current BB basics or point me to a good site.
I'm interested in learning about internal v. external cups(?), sizes, what's compatible with what etc. Basically some general info to fire up my understanding.
Thanks
TMT
I'm interested in learning about internal v. external cups(?), sizes, what's compatible with what etc. Basically some general info to fire up my understanding.
Thanks
TMT
10-16-12, 07:29 AM
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It's a start:
https://www.parktool.com/blog/repair-...ottom-brackets
https://www.parktool.com/blog/repair-...ottom-brackets
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10-16-12, 07:31 AM
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BB30 is a standard where the bearings are pressed into the BB shell. The crank spindle is then an interference fit into the bearings' inner races.
The external bearing BBs for threaded bottom brackets are available in (as far as I know) english and italian thread. The bearings are outboard of the BB shell, but they are threaded into it in the normal way, although the shell does need to be faced more accurately than with a standard "internal" BB. The crank spindle is much the same as a BB30 one, and in fact I'm not sure some of them aren't cross-compatible. Most, if not all, of these new crank spindles are integrated into the right-hand crank, and the left-hand crank tends to be a splined fitting with a pinch-bolt to clamp the crank on after it's pushed on using a bolt that threads into the end of the spindle.
There are some compatibility issues between different brands of these so-called "two-piece" cranks and the corresponding bearings, but someone else will need to explain which they are, since I'm not sure.
As for conventional BBs, there are, in addition to square-taper, several splined standards, of which I can remember 3: Octalink V1, Octalink V2 and ISIS, of which the first and second are Shimano designs, and the last is the rival standard. I think there might be a Truvativ-specific one as well, or Truvativ might use ISIS, I can't remember.
The external bearing BBs for threaded bottom brackets are available in (as far as I know) english and italian thread. The bearings are outboard of the BB shell, but they are threaded into it in the normal way, although the shell does need to be faced more accurately than with a standard "internal" BB. The crank spindle is much the same as a BB30 one, and in fact I'm not sure some of them aren't cross-compatible. Most, if not all, of these new crank spindles are integrated into the right-hand crank, and the left-hand crank tends to be a splined fitting with a pinch-bolt to clamp the crank on after it's pushed on using a bolt that threads into the end of the spindle.
There are some compatibility issues between different brands of these so-called "two-piece" cranks and the corresponding bearings, but someone else will need to explain which they are, since I'm not sure.
As for conventional BBs, there are, in addition to square-taper, several splined standards, of which I can remember 3: Octalink V1, Octalink V2 and ISIS, of which the first and second are Shimano designs, and the last is the rival standard. I think there might be a Truvativ-specific one as well, or Truvativ might use ISIS, I can't remember.
Last edited by Airburst; 10-16-12 at 07:47 AM. Reason: typo
10-16-12, 07:31 AM
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I would think that you need to narrow down what type of information you need by decades what type and year of bike do you have and what is on there now
10-16-12, 07:53 AM
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Half-step triple, using double gear ~~~ 6400 STI rebuild walkthrough ~~~ Want 8/9/10s @126mm OLD? OCR. ~~~ Shimano cassette body overhaul ~~~ Ergopower Escape wear repair ~~~ PSA: drivetrain wear
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Sheldon Brown's bike info ~~~ Park Tools repair help
Half-step triple, using double gear ~~~ 6400 STI rebuild walkthrough ~~~ Want 8/9/10s @126mm OLD? OCR. ~~~ Shimano cassette body overhaul ~~~ Ergopower Escape wear repair ~~~ PSA: drivetrain wear
List of US/Canada bike co-ops ~~~ Global list
10-16-12, 08:45 AM
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Last edited by Homebrew01; 10-16-12 at 01:05 PM.
10-16-12, 10:21 AM
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Shows a lack of imagination, don't it.
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Sheldon Brown's bike info ~~~ Park Tools repair help
Half-step triple, using double gear ~~~ 6400 STI rebuild walkthrough ~~~ Want 8/9/10s @126mm OLD? OCR. ~~~ Shimano cassette body overhaul ~~~ Ergopower Escape wear repair ~~~ PSA: drivetrain wear
List of US/Canada bike co-ops ~~~ Global list
Sheldon Brown's bike info ~~~ Park Tools repair help
Half-step triple, using double gear ~~~ 6400 STI rebuild walkthrough ~~~ Want 8/9/10s @126mm OLD? OCR. ~~~ Shimano cassette body overhaul ~~~ Ergopower Escape wear repair ~~~ PSA: drivetrain wear
List of US/Canada bike co-ops ~~~ Global list
10-16-12, 10:25 AM
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The great thing about standards is that there are so many to choose from.
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10-16-12, 08:18 PM
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