# Crankset side loading adjustment for SRAM Red 2012 BB30 and other cranksets



## myhui (Aug 11, 2012)

SRAM uses a flimsy plastic ring with an easily stripped screw to prevent the crank shaft from shifting side to side.









The step 10 in green above shows the movement I'm talking about.

The purple steps 3, 9, 10 show how to adjust that tiny plastic ring to push the crank arm to the left and keep it there.









My crank set developed a "croc croc croc" sound, and the LBG's mechanic diagnosed it to missing spacers between the crank arms and the BB that further prevents the crank shaft from shifting side to side.

I find this design from SRAM rather poor.

I wonder how do other component makers do this? Just use different thickness washers to act as shims to fill up that space and prevent sideways movement? The bearings certainly are never meant to withstand sideways movement, or to prevent it. So preventing this movement has to be done in some other way.

To use an automotive analogy, this is the job of the thrust bearing that prevents the engine crank shaft from being pushed sideways as the clutch's friction disk clamps on to the flywheel. The thrust bearing is usually at the opposite end of the crank shaft from the end that connects to the flywheel.


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## MR_GRUMPY (Aug 21, 2002)

I wonder how do other component makers do this?

Shimano doesn't use stupid washers......Campy does.
.


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## Pirx (Aug 9, 2009)

MR_GRUMPY said:


> Shimano doesn't use stupid washers......Campy does.
> .


Yep, but Campy uses a smart washer, known as the "wavy washer". Far and away the best, most simple to install system, with no adjustments required, ever.


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## looigi (Nov 24, 2010)

In these cranks, the bearings support the thrust loads. The washers simply fill in the gap so there is no longitudinal play of the crank spindle in the inner races of the bearings. The trust is still applied to the inner races.


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## goodboyr (Apr 19, 2006)

"Smart washer"......…lol. Of course its smart.......its Campy! Its just a wavy washer for the rest of us.


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## myhui (Aug 11, 2012)

looigi said:


> In these cranks, the bearings support the thrust loads. The washers simply fill in the gap so there is no longitudinal play of the crank spindle in the inner races of the bearings. The trust is still applied to the inner races.


But there is no provision for securing the crank shaft to the bearings in that direction of play. If they shift positions, there will be noise and wear.

I know ... Use carbon fiber and Teflon shims.


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## cxwrench (Nov 9, 2004)

myhui said:


> But there is no provision for securing the crank shaft to the bearings in that direction of play. If they shift positions, there will be noise and wear.
> 
> I know ... Use carbon fiber and Teflon shims.



Read looigi's post again. The plastic washers take up any space that would allow the spindle to move side to side. Not all frames are manufactured exactly to spec. In fact, the spec has some +/- built in to the manufacturing tolerances because the designers of BB30 know how 'things work' in the factories. Campy and some others use the wavy washer. SRAM uses the plastic washers and the adjustable preload collar. Both work. They're not exactly fancy, but until every frame is made exactly the same, to the 1/100th of a mm, some method of easily adjusting the bearing preload will be needed. 
The plastic washers are exactly the "provision for securing the crank shaft to the bearings" that you think doesn't exist. 

Your arguments are getting tiring. If you'd just trust the information that many experienced posters are trying to give you, you'd find all this stuff is pretty easy to accomplish.


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## myhui (Aug 11, 2012)

(deleted)


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## myhui (Aug 11, 2012)

How does Shimano do it without those washers? (And not get sued by Specialized)


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## MR_GRUMPY (Aug 21, 2002)

Think of a threadless headset.

Would you want a headset with a "wavy" washer, to take up slack?
.


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## myhui (Aug 11, 2012)

cxwrench said:


> The plastic washers take up any space that would allow the spindle to move side to side.


You are right. (and ... you are always right)

I misunderstood the physical arrangement of the BB.

Now I see that the outside face of the bearings actually touch the washers.

Thus the distance between crank arm plus the washers will let the bearings fit snugly between them. The inside face of the bearings are supported by the C-ring washers that are seated into the groove.

In other words, every component in the following diagram is meant to squeeze tightly against each other, with the C-ring washer at one end, and the crank arm at the other:


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## myhui (Aug 11, 2012)

MR_GRUMPY said:


> Think of a threadless headset.
> 
> Would you want a headset with a "wavy" washer, to take up slack?


Of course not.

Campagnolo's latest design no longer uses a wavy washer, and it looks like quite an interesting design. I'm not 100% sure how that set screw works. I hope it doesn't just secure that ring onto the crank shaft, as that may not be strong enough.









Here is their previous design with the wavy washer:


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## MR_GRUMPY (Aug 21, 2002)

Would you want your headset held tight by a ring and a set screw??
.
.


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## cxwrench (Nov 9, 2004)

myhui said:


> How does Shimano do it without those washers? (And not get sued by Specialized)


Sounds like you now understand how the SRAM system works pretty well. Shimano is different in that you actually adjust the preload on the bearings by tightening the large nut that pulls the crank arm onto the spindle. The Shimano spindle is the same outside diameter all the way across, so the non-drive crank arm can end up anywhere within a small area depending on exactly how wide the frame is. 
How they don't get sued by the big 'S' is a mystery to me.


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## myhui (Aug 11, 2012)

cxwrench said:


> Sounds like you now understand how the SRAM system works pretty well.


Yes, and I thank you for your patience and explanations.



cxwrench said:


> Shimano is different in that you actually adjust the preload on the bearings by tightening the large nut that pulls the crank arm onto the spindle. The Shimano spindle is the same outside diameter all the way across, so the non-drive crank arm can end up anywhere within a small area depending on exactly how wide the frame is.


I see now. Thanks. That seems like a more easily adjustable and robust design compared to designs from SRAM and Campagnolo. You can at least adjust the preload without major disassembly. It's somewhat like adjusting the valve clearance via a nut on a piston engine versus adjusting the clearance via swapping shims.

I looked throughout Shimano's down-loadable technical docs, and they are quite a bit worse than what SRAM and Campagnolo had. I couldn't find anything from Shimano that is meant for the BB30 standard.


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## cxwrench (Nov 9, 2004)

myhui said:


> Yes, and I thank you for your patience and explanations.
> 
> 
> I see now. Thanks. That seems like a more easily adjustable and robust design compared to designs from SRAM and Campagnolo. *You can at least adjust the preload without major disassembly. It's somewhat like adjusting the valve clearance via a nut on a piston engine versus adjusting the clearance via swapping shims*.
> ...


Good analogy. 

Shimano doesn't make anything in BB30, that's why you can't find anything in techdocs. They also don't make thread less headsets...they never wanted to pay royalties to Cane Creek.


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