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Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

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Old 11-17-05, 08:52 PM   #1
poopncow
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Bottom Bracket Preload???

Ok, I'm spoiled by cartridge this and cartridge that.

How much preload should an old style, loose balls, cups and lock ring BB get? Should there be any play (up down) on the spindle? What is the best indicator that the cups are tight enough?
If this did not have such a nicely ground spindle (70's sugino) I would chuck it for a maintenance free UN-72.

Crunching is too tight ... right???
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Old 11-17-05, 09:01 PM   #2
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Smooth with no play.
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Old 11-17-05, 09:12 PM   #3
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I was afraid of an answer like that. If the 2 factors shall not meet very well, should it be as smooth as possible without play?
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Old 11-17-05, 09:22 PM   #4
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No play,no binding, no foul.
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Old 11-17-05, 09:26 PM   #5
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Quote:
Originally Posted by poopncow
I was afraid of an answer like that.
Don't fear the truth.
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Old 11-17-05, 10:15 PM   #6
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gosh, how did you guys use to adjust all that stuff all the time? The machining / honing has to be perfect to get rid of all the play at all locations for a full rotation. There is just a small (.0005?) bit of play at 9 oclock and no play else where on the non drive side and play in other areas on the drive side. With the crank on and fix wheel hooked up, it spins for quite a while. just wondering if I should set the cones closer?
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Old 11-17-05, 10:17 PM   #7
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I mean I have to close my eyes and shake the crank arm to feel the play at the end of the arm.
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Old 11-18-05, 12:30 AM   #8
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Quote:
Originally Posted by poopncow
I mean I have to close my eyes and shake the crank arm to feel the play at the end of the arm.
The best way to do this is with the crank arms installed. Grab the end of the arms and shake. If you can feel play in the axle it's time to tighten up the adjustable cup. Keep tightening and shaking until any play goes away and the axle still turns freely. This is definitely a trial and error process. Hubs and headsets are exactly the same, except the way you test the headset is to apply both brakes and rock back and forth on the handle bars, and with wheels/hubs you grab the rims and rock the wheel until there is no appreciable play. In all cases there will be a point of adjusting a bearing cup (or cone, or race) where the play goes away, but the operation remains smooth. Any tightness, grittyness, binding, or "non-smoothness" means that you need to back off. After you do a few you will learn to have a feel for the process and often get it done in one shot.

What sydney said, but in more detail ;-) He's a minimalist ;-)
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Old 11-18-05, 12:32 AM   #9
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Quote:
Originally Posted by poopncow
gosh, how did you guys use to adjust all that stuff all the time? The machining / honing has to be perfect to get rid of all the play at all locations for a full rotation. There is just a small (.0005?) bit of play at 9 oclock and no play else where on the non drive side and play in other areas on the drive side. With the crank on and fix wheel hooked up, it spins for quite a while. just wondering if I should set the cones closer?
Yes, it's a little too loose if you have any play at any location at all. What will happen with that looseness is the load will be concentrated on a single ball or two at that point and the wear will accelerate. Better too tight with extra friction than too loose (because it'll wear into correct specs eventually).

Due to the gap in the threads, when you tighten the lockring, it will actually pull the cup outwards slightly, thus opening up some clearance. So... with the cup adjusted just perfect so there's no play, tighten it up an additional 1/16-1/8th of a turn, then tighten the lockring, which will pull the cup back out to the previous setting of perfectly smooth. Depending upon how square the facing is and how clean the threads, this additional amount will vary.
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Old 11-18-05, 12:33 AM   #10
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Quote:
Originally Posted by poopncow
gosh, how did you guys use to adjust all that stuff all the time? The machining / honing has to be perfect to get rid of all the play at all locations for a full rotation. There is just a small (.0005?) bit of play at 9 oclock and no play else where on the non drive side and play in other areas on the drive side. With the crank on and fix wheel hooked up, it spins for quite a while. just wondering if I should set the cones closer?
The precision with which you can do this adjustment by feel is pretty amazing. Those things attached to your wrists are incredible tools if you practice a little. Brain surgery is not yet done with robots. Think about it.
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Old 11-18-05, 07:45 AM   #11
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Quote:
Originally Posted by DannoXYZ
Yes, it's a little too loose if you have any play at any location at all. What will happen with that looseness is the load will be concentrated on a single ball or two at that point and the wear will accelerate. Better too tight with extra friction than too loose (because it'll wear into correct specs eventually).

Due to the gap in the threads, when you tighten the lockring, it will actually pull the cup outwards slightly, thus opening up some clearance. So... with the cup adjusted just perfect so there's no play, tighten it up an additional 1/16-1/8th of a turn, then tighten the lockring, which will pull the cup back out to the previous setting of perfectly smooth. Depending upon how square the facing is and how clean the threads, this additional amount will vary.
nicely put. i'll drag out jobst again:

http://www.yarchive.net/bike/ball_bearings.html
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Old 11-18-05, 08:14 AM   #12
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When adjusting a loose ball type bottom bracket, I tighten the adjustable cup until resistance is felt indicating binding in the bearings, next back off the cup 1/8 turn or so to allow the bearings to spin smoothly. Lastly, tighten the lock nut.
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Old 11-18-05, 09:08 AM   #13
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Everyone, Thanks for all the advice. You detailed explainations are well appreciated! Especially for clearing up the play thru out the rotation question. I will go back and tighten up the cup a little more to get rid of all play (yes will use the arms as a lever)

I used to adjust valve clearances on motorcycles and Datson Z cars and did machine work for a few summers. So I am very familiar with the effect of play in threads and how to compensate for it. Its good to have some experience
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Old 11-18-05, 09:15 AM   #14
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Quote:
Originally Posted by DannoXYZ
Due to the gap in the threads, when you tighten the lockring, it will actually pull the cup outwards slightly, thus opening up some clearance.
Unless, of course, in the process of tightening the lockring, you also turn the adjustable cup a little too. You need to play with it all a little bit and figure out where you want the cup to end up so that tightening the ring will tighten it up but also put it outward...just so.
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Old 11-18-05, 01:28 PM   #15
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Originally Posted by bostontrevor
Unless, of course, in the process of tightening the lockring, you also turn the adjustable cup a little too. You need to play with it all a little bit and figure out where you want the cup to end up so that tightening the ring will tighten it up but also put it outward...just so.
Isn't that why one typically uses a bottom braket pin spanner and the bb lockring tool when adjusting a bb? One to hold the adj cup in place; one to tighten the lockring?
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Old 11-18-05, 02:37 PM   #16
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Nope, the pin spanner isn't designed for holding the cup in place, just removing it. You can bend or break the pins if you're not careful, or so I'm told. Not all cups take pins, either. I've got at least one that's just got a notch for a lockring spanner.
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