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Old 04-01-07, 05:43 PM   #1
alumrock12
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eccentric bottom brackets

is there a website for this? i didn't see much on sheldon brown..

i'm looking for maintenance and adjusting info for some future knowledge in repairs...
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Old 04-01-07, 05:58 PM   #2
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Quote:
Originally Posted by alumrock12
is there a website for this? i didn't see much on sheldon brown..

i'm looking for maintenance and adjusting info for some future knowledge in repairs...
take your crank/bb off.

undo whatever bolts hold yours (the EBB) in (pinch/expanding wedge/set screw)

pull it out. take it apart. clean it. regrease it.

reverse process.

it ain't rocket surgery.
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Old 04-01-07, 06:25 PM   #3
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unless it is a seald bb
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Old 04-01-07, 06:54 PM   #4
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but if i take the bottom bracket out, and the bolts holding it in its position, how do i know what how much to screw the bolts back in? since the bolts determine how foward or backward the bb is.
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Old 04-02-07, 12:51 AM   #5
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Quote:
Originally Posted by alumrock12
but if i take the bottom bracket out, and the bolts holding it in its position, how do i know what how much to screw the bolts back in? since the bolts determine how foward or backward the bb is.
huh?

you'll know how far to screw them in by how tight the chain is....no?
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Old 04-02-07, 06:27 AM   #6
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this is making no sense, i need some pics
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Old 04-02-07, 07:08 AM   #7
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Quote:
Originally Posted by taylor p
unless it is a seald bb
how does that make any difference?
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Old 04-02-07, 07:09 AM   #8
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Quote:
Originally Posted by taylor p
this is making no sense, i need some pics

no, you need to understand how an eccentric bottom bracket shell works. the EBB is not the bottom bracket iteself, but the shell that the BB sits in. the BB sits in the EBB shell, offcenter, so that when you turn the EBB, it tightens/loosens chain tension. which is adjustable to tune in chain tension on singlespeeds. the SS world has adopted them from the tandem crowd, that has used them for years to dial in timing chain tnesion.

whether the BB is sealed or not makes no difference when taking the EBB out/cleaning it.

the interweb is your friend!
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Old 04-02-07, 05:59 PM   #9
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Quote:
Originally Posted by scrublover
no, you need to understand how an eccentric bottom bracket shell works. the EBB is not the bottom bracket iteself, but the shell that the BB sits in. the BB sits in the EBB shell, offcenter, so that when you turn the EBB, it tightens/loosens chain tension. which is adjustable to tune in chain tension on singlespeeds. the SS world has adopted them from the tandem crowd, that has used them for years to dial in timing chain tnesion.

whether the BB is sealed or not makes no difference when taking the EBB out/cleaning it.

the interweb is your friend!
wow never heard of one before .
does both sides of the "ebb" rotate together? other wise wouldn't you get a lop sided crank?
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Old 04-02-07, 07:35 PM   #10
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Quote:
Originally Posted by taylor p
wow never heard of one before .
does both sides of the "ebb" rotate together? other wise wouldn't you get a lop sided crank?
yes! all you had to do was Google it and you'd get it - its basically a rotating shell you put your normal BB into



I'd agree w/ the above posts, you'd just tighten it back up so your chain is tight
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Old 04-02-07, 08:15 PM   #11
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yes, i belive both sides move together as one. how do i know HOW much to spin the bolts? until it has enough tension? on which gear should i have it on when tensioning the chain... heres a pic for those of you who've never seen it before.
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Old 04-02-07, 08:28 PM   #12
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Old 04-02-07, 08:30 PM   #13
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or... do i have the idea all wrong. is it that you move the bottom bracket shell to where ever you want it/where ever the chain become taught... and then you hold it in that position and tighten the bolts?

or... do you really have to spin the bolts a certain number of times and that is what moves the shell? how would i go about doing that? shift into a certain gear when tightning it?
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Old 04-02-07, 09:01 PM   #14
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how does that work when you have a rear Derailleur that takes care of your chain tension?
sorry i'm not answer your questions
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Old 04-02-07, 11:43 PM   #15
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say:

if i move the bracket shell really close to the rear. the chain will hang lose. if i move the bracket too far foward, the chain won't shift well right? it'll be really tight at least right? how do i know how far to move the shell?
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Old 04-02-07, 11:55 PM   #16
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you spin the bolts as much as is specified for proper torque.

are you making a mountain out of a molehill?
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Old 04-03-07, 05:11 AM   #17
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Quote:
Originally Posted by mx_599
you spin the bolts as much as is specified for proper torque.

are you making a mountain out of a molehill?
yes
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Old 04-03-07, 05:28 AM   #18
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This isn't a chain tensioning issue, the derailluer will take care of that. What we are dealing with here is, center of gravity VS. ground clearance.
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Old 04-03-07, 06:10 AM   #19
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so, i'm certainly not an expert on ebb's here, but i think you're barking up the wrong tree.

for the most part, you don't need to worry about the ebb position when you have a rear derailleur. the ebb is there to adjust chain tension if you're running singlespeed or an internally geared hub. these setups require an exact bb-to-axle distance for proper chain tension. setups with a rear derailleur do not, the derailleur will take up chain slack.

yes, the position of the ebb will affect your center of gravity and ground clearance, so if you liked the setup before i'd just try and put it back in the same place. if you have a problem with ground clearance, you can rotate it up but then you will need to readjust your seat and possibly bar position.

so in conclusion, if you're running gears, best to leave it alone.
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