SRAM BB30 Crankset Installation

[Valbrona]

1/ The instructions say put 48-54Nm into the crank bolt (on the DS side) ... and then 'tap with a hammer to fully seat crank arm'. Surely ~50Nm is enough to 'fully seat the crank arm'. I don't get it ...

2/ The plastic preload collar looks like it might break if I look at it too hard - give me a wave washer any day. Just to clarify ... Do you adjust the preload collar after putting your ~50Nm into the crank bolt?

I don't like these 'instructions in pictures' way of doing things, much preferring the text-heavy Campag approach.

Thanks folks.

[Rick]

The crank arm is not tight against the bottom bracket when torqued. The CRANK SPINDLE is longer than the BB is wide, so you tap the drive side to make sure that side is fully seated against the BB30 bearings. No matter how much you torque the crank bolt the cranks will still slide laterally about 1-2mm.

The preload collar looks fragile....but it clamps onto the crank spindle by friction when the small locking screw is tightened. Then, it is MUCH stiffer against lateral loads than the wave washer would be. The wave washer is actually quite soft against lateral loads. That's why so many BB30 setups click and groan.

I have been through this with my own BB30 cranks (Sram Force and Red) and believe me, the preload collar works much better.

The preload collar doesn't have to be very tight against the bearing dust cover (assuming you "seated" the other side snugly with a light mallet blow). In fact, the plastic threads will strip if you try to force too much torque on them. You are just "taking up the remaining space" on the spindle, then locking the ring down tight with the locking screw.

[goodboyr]

And dont over tighten the locking screw. It just needs to be snug. Many have stripped the heads of these tiny screws by over tightening.

[DMF]

I consider that lockring a complete joke. Seen way too many coming undone, the owner not taking notice, and having the bearings beaten up by the lateral play.

Do as follows,

A) Remove crank.
B) Remove lockring.
C) Soak lockring in flammable liquid of your choice.
D) Set said lockring on fire in well ventilated area.
E) Remount cranks with appropriate number of microwashers, mount and dismount crank trying different setups of washers until perfection. No lateral play, no pressure on bearings.

Do it right, do it once.

[Valbrona]

Thanks. What well informed responses.

Remount cranks with appropriate number of microwashers, mount and dismount crank trying different setups of washers until perfection. No lateral play, no pressure on bearings..

I like the sound of that. However, you can set any part of your bike up 'perfect' in your kitchen or whatever, but when you ride it quickly shows the 'poor adjustments'. Using washers as you suggest might be quite a laborious process.

The thing with a spring washer is that it will micro-adjust while in use. Simple.

I can't help but think the SRAM crankset I have is a bit of a dud. If it didn't have the 'BB30' logo on it I might have thought it was a BB386 crankset.

[highdraw]

The level of fail in this thread already is beyond description. BB/Crank relationships are the most misunderstood aspect of any racing bike.

The notion that wavewashers is the reason that BB30 clicks and groans is rubbish. The reason why BB30 clicks and groans is because of tolerances and lack of Loctite that cause BB outer races to toggle within their bores and lateral preload is a small contributor to this condition.

The fact that a wavewasher is better or worse than a lockring is also baloney. They are both effective.

Goodboyr's assertion about not overtorquing the set screw is a good one.

OP...follow the instructions. Staccato force helps seat the spindle and net torque pulls them together. The instructions were developed based upon best practice. No...torque alone will not be as effective in seating the spindle as torque + light hammer tap.

OP...your wavewasher versus lockring bias is your problem and not anybody else's. The industry is replete with both including Campagnolo and both are very effective for different reasons.

Your question about when to adjust the lockring reflects your lack of insight. Of course you adjust the position of the lockring 'after' the crank is torqued together which dictates effective spindle length.

PS: a last note...DMF and the guy who does a dis-service to the industry with Campag UltraTorque cranks...the Rogue Mechanic...completely mislead the uneducated masses who don't know any better. Precisely shimming spacer width to control preload is a ridiculous way to set up any crank. Stick with design intent...either wavewasher or locking preload collar...both are very effective. I have set up hundreds of cranks of all varieties and have never had a problem with noise or reliability of either design. Shimano's duel pinch bolt straight spline adjustable mechanical preload is simply superb as well. Ridiculous to tune axial preload with trial and error of adding/subtracting spacers to dial preload precisely...only for guys who don't know any better.

[highdraw]

Thanks. What well informed responses.

Remount cranks with appropriate number of microwashers, mount and dismount crank trying different setups of washers until perfection. No lateral play, no pressure on bearings..

I like the sound of that. However, you can set any part of your bike up 'perfect' in your kitchen or whatever, but when you ride it quickly shows the 'poor adjustments'. Using washers as you suggest might be quite a laborious process.

The thing with a spring washer is that it will micro-adjust while in use. Simple.

You are at least starting to get the picture so there is hope.

[Valbrona]

I expect to find plastic collars on a seatpost holding a light on. Not on a BB axle. Would have thought a metal arrangement would have been obvious.

[highdraw]

I expect to find plastic collars on a seatpost holding a light on. Not on a BB axle. Would have thought a metal arrangement would have been obvious.

You should withhold judgment honestly because you don't know any better. Sorry to be blunt but that is the fact. Sram performs FEA and stress analysis on every single part they manufacture. Plus to skirt liability, they perform copious lab testing which correlates to road load data based upon strain gaging their bikes. Lateral crank spindle loading is light relative to rather extreme vertical loading due to pedal forces and rider weight. The plastic lockring is perfectly fine no matter how much you disparage it. Metal comes with a weight penalty versus plastic. Engineered plastics are prevalent in many designs and even comprise gears inside transmissions. If you don't have a background in design, you are farther ahead to defer to those that do.

[DMF]

Bighdraw, I would imagine the wave washer is there for one reason and one reason alone, it isn't feasible time wise for a workshop to shim cranks in place... It is so to speak of economical value to have a quick solution. In a perfect world though, that wavy washer wouldn't put sideways pressure on the bearing thus adding a slight bit of drag.

This is WW after all, minute incremental improvements and so forth...

For customers bikes, I only do this in a few except cases.

I wouldn't mind the threaded lockring solution if they could just make it out of metal instead of the most brittle piece of plastic known to mankind... It really is a decent solution, SRAM just made a POS construction of it...

Edit, as for the bicycle industry FEA testing, real world testing, et al... I imagine the history speaks quite loudly for itself and admittedly bad constructions constantly circulate the market, sometimes for years, before being withdrawn and re-approached. This is on par, and this would presumably be a very typical "one of those".

[highdraw]

Doesn't matter what a bike shop time and labor constraint is. Precise shimming with spacers as you propose is ill fated. It is almost impossible to get spacing just right to isolate the cranks with hard spacers thru trial, error and even measurement. Further, having no adjustability is a poor choice as well as bearings tend to bed with time and a wave washer compensates for this naturally and lockrings can be adusted in less than 30 seconds...and preload should be checked from time to time because bearings do bed with time. A .005" hard spacer width change is the difference between axial play and too much bearing preload.

So, your proposal is flawed and not best practice. Just stating the reality of it...a waste of time.

Lastly, there is nothing wrong with Sram's lockring....only the guys that work on it.
Carbon Fiber bicycles most of use ride are compromised of 30% epoxy polymer...a load bearing, safety critical part that we trust our lives on. Metal parts fail as well if poorly engineered. A plastic lockring FWIW is directionally correct to the WW charter as plastic is lighter than metal by volume.

Bighdraw, I would imagine the wave washer is there for one reason and one reason alone, it isn't feasible time wise for a workshop to shim cranks in place... It is so to speak of economical value to have a quick solution. In a perfect world though, that wavy washer wouldn't put sideways pressure on the bearing thus adding a slight bit of drag.

This is WW after all, minute incremental improvements and so forth...

For customers bikes, I only do this in a few except cases.

I wouldn't mind the threaded lockring solution if they could just make it out of metal instead of the most brittle piece of plastic known to mankind... It really is decent solution, SRAM just made a POS construction of it...

[Rick]

After numerous fails with the wave washer, precise shimming with spacers is how I got my prior BB30 setup working properly.
I hesitate to recommend it, because I have a lot of micrometers and feeler gages, etc, and lots of experience, so I can see how it might be problemmatic for the average home mechanic.
But it does work. Remember that BB30 bearings (and others) really can take a little side preload without causing problems. It doesn't cause any extra "drag", and in fact the lateral load cpacity of the bearing is greater than the radial load capacity.

But when I got the new Red setup, with lock washer, I immediately thought "Aha! SRAM got rid of that ridiculous wave washer!"

Regarding the Wave washers vs. other methods (precise shimming, lock washers, etc): This has been discussed thoroughly in prior threads. If wave washers are adequate, then why did Sram (and others) stop using them ? They are certainly much easier to install than any of the other methods.

But I actually agree that the SRAM lock ring is too fragile. I buggerred one on initial installation and had to buy a couple spares. I believe it is adequate once installed, but must be installed very carefully to avoid stripping threads, both the plastic "axle" threads and the threads of the locking screw. At one time I was looking into trying to replace it with the similar ROTOR locking ring (metal), but I never followed through with that.

[highdraw]

After numerous fails with the wave washer, precise shimming with spacers is how I got my prior BB30 setup working properly.
I hesitate to recommend it, because I have a lot of micrometers and feeler gages, etc, and lots of experience, so I can see how it might be problemmatic for the average home mechanic.
But it does work. Remember that BB30 bearings (and others) really can take a little side preload without causing problems. It doesn't cause any extra "drag", and in fact the lateral load cpacity of the bearing is greater than the radial load capacity.

But when I got the new Red setup, with lock washer, I immediately thought "Aha! SRAM got rid of that ridiculous wave washer!"

Regarding the Wave washers vs. other methods (precise shimming, lock washers, etc): This has been discussed thoroughly in prior threads. If wave washers are adequate, then why did Sram (and others) stop using them ? They are certainly much easier to install than any of the other methods.

No. I recognize this is too deep for most...lol. You so called 'fixed' your BB30 by not addressing the root cause. You artificially introduced likely more preload by hard spacing your BB30 to quiet it when you didn't address why it was creaking....the bearings were not secure in their respective bores. This the vast majority of time requires Loctite. Once BB30 bearings are glued to respective bores than the design is much less sensitive to preload. So you tamed your BB30 with likely peril to premature bearing wear common to those who use ridiculous hard spacing to induce more preload than is desired. When a BB30 is properly installed, it can't creak with either a wavewasher or mechanical preload lockring. Sadly few understand the root cause.

As to why Sram stopped using a wave washer...is because it still put too much onus on guys like you who even ask. The answer is because a wave washer application still takes proper hard spacing to place the wave washer in the sweet spot of its force/deflection point....which most don't understand either. So they are basically dummy proofing their design with a preload lockring. Shimano does the same thing with their cranks but guess what? Likely 50% who install them don't understand the simple practice of how to adjust mechanical preload with the little plastic wheel supplied either. The universal problem with cranks and BB's is the average consumer that tries to work on them don't understand the design.

[Rick]

Sadly few understand the root cause.

Sorry, highdraw, but I had already tried Loctite 609 and 642. I am a mechanical design engineer with 35+ years experience. I am way ahead of you on this particular issue. If your BB30 is working fine, I applaud you and am happy. But lots of other people have had persistent repeated problems that were solved by a "hard" mounting scheme on the axle. You can use the search function for the history. And you can just google it to see that BB30 installation problems are ubiquitous. Loctiting the bearings is ONE ASPECT of the problem.

[highdraw]

Sadly few understand the root cause.

Sorry, highdraw, but I had already tried Loctite 609 and 642. I am a mechanical design engineer with 35+ years experience. I am way ahead of you on this particular issue. If your BB30 is working fine, I applaud you and am happy. But lots of other people have had persistent repeated problems that were solved by a "hard" mounting scheme on the axle. You can use the search function for the history. And you can just google it to see that BB30 installation problems are ubiquitous. Loctiting the bearings is ONE ASPECT of the problem.

Sorry but way ahead of you. You don't know what you are talking about. I worked in the industry on the design. Sorry to be the bearer of bad news. The only people that have problems with BB30 are those like yourself that don't understand the design and understand root cause. This thread has a nice subset of those that are making judgments without understanding the physics involved. When BB30 is set up properly 'it can't creak' be it with wave washer or mechanical preload locking collar. Both are effective.