Octalink crank/bb trouble!

curby said:

I have never used an Isis or Octalink setup (hope i never have to...) but somebody showed up for the saturday morning ride today and their ultegra level double crank and bb was making a racket!... one or both of the arms is moving out of phase, every half a revolution the cranks sink, quite noticeably... and a click/creak to go with it... you can even make it happen by grabbing both pedals by hand and pushing down, rotate the cranks 180 degrees and push them back...

any ideas what was done wrong?

One-or-both of the crank bolts is loose ... by now, the splines on the bottom bracket spindle which "register" the crank arms have probably damaged the crank arm(s).

Sadly, an inexpensive 8mm Allen wrench would have solved the problem ...

Worth tightening to see if the crank arm can be used; but, a replacement should be anticipated.

FWIW. You can't blame the design ... it is like blaming an automobile manufacturer for a wheel falling off of a car if you don't tighten the wheel's lug nuts.

curby said:

I have never used an Isis or Octalink setup (hope i never have to...) but somebody showed up for the saturday morning ride today and their ultegra level double crank and bb was making a racket!... one or both of the arms is moving out of phase, every half a revolution the cranks sink, quite noticeably... and a click/creak to go with it... you can even make it happen by grabbing both pedals by hand and pushing down, rotate the cranks 180 degrees and push them back...

any ideas what was done wrong?

Somebody thought a torque wrench and blue loctite, wasn't worth the expesnse. Like the old motor oil ad, "Yous can pay me now, or yous can pay me latter".

lks said:

Somebody thought a torque wrench and blue loctite, wasn't worth the expesnse. Like the old motor oil ad, "Yous can pay me now, or yous can pay me latter".

Or at least a 12" adjustable wrench to crank the allen key, the ability to calculate torque and some cheap grease on the crank bolt thread and axle splines.

artemidorus said:

Or at least a 12" adjustable wrench to crank the allen key, the ability to calculate torque and some cheap grease on the crank bolt thread and axle splines.

Why would you put grease on the crank bolt threads, unless you want to luricate them so they can work their way out? Use Blue loctite, it's an anti-seize lubricant and semi pemanent thread locker. Use grease on the splines, locktite anti-seize compound is best. But if you are out of beer money, stick your finger under your car for good enough grease.

lks said:

Why would you put grease on the crank bolt threads, unless you want to luricate them so they can work their way out?

Grease prevents any metallic reaction between parts. And they won't work their way out if the bolt has been torqued down properly.

lks said:

Why would you put grease on the crank bolt threads, unless you want to luricate them so they can work their way out? Use Blue loctite, it's an anti-seize lubricant and semi pemanent thread locker. Use grease on the splines, locktite anti-seize compound is best. But if you are out of beer money, stick your finger under your car for good enough grease.

The crank bolt is bound not by Loctite or any other glue, but by the force of metal against metal generated by adequate torque. Grease helps this process, as it prevents friction from stopping the bolt getting to an adequate degree of tightness.
Just to reinforce this - grease prevents a bolt from working out, through allowing the adequate torque locking of the bolt, and it does not help it to work its way out.
Loctite is for use in situations where the frailty of the item prevents adequate torque locking, such as with those tiny little screws in your DA shifter.

artemidorus said:

The crank bolt is bound not by Loctite or any other glue, but by the force of metal against metal generated by adequate torque. Grease helps this process, as it prevents friction from stopping the bolt getting to an adequate degree of tightness.
Just to reinforce this - grease prevents a bolt from working out, through allowing the adequate torque locking of the bolt, and it does not help it to work its way out.
Loctite is for use in situations where the frailty of the item prevents adequate torque locking, such as with those tiny little screws in your DA shifter.

Guess the aircraft and race car industry is wasting a lot of time and money, using thread locker and safety wire on the millions of bolts and nuts they torque down properly. The bike industry uses thread locker on some bolts, don't they have torque wrenches? Why doe's Campy apply thread locker to the crank bolts that come with their Record carbon cranksets? My $25 a piece titanium after market crank bolts came with thread locker. Ask any mechanic, if he has ever said, " I had to RE-TORQUE it". Of course, most properly torqued nuts and bolts don't come loose. Most, not all.

lks said:

Guess the aircraft and race car industry is wasting a lot of time and money, using thread locker and safety wire on the millions of bolts and nuts they torque down properly. The bike industry uses thread locker on some bolts, don't they have torque wrenches? Why doe's Campy apply thread locker to the crank bolts that come with their Record carbon cranksets? My $25 a piece titanium after market crank bolts came with thread locker. Ask any mechanic, if he has ever said, " I had to RE-TORQUE it". Of course, most properly torqued nuts and bolts don't come loose. Most, not all.

The vibration exposure in planes and cars is going to be different and may account for different thread preparation regimens.
I'll stick to my original assertation - crank bolts don't need Loctite but they do need lubrication and adequate torque. What happened to all the engineers that used to abound on this forum?

artemidorus said:

The vibration exposure in planes and cars is going to be different and may account for different thread preparation regimens.
I'll stick to my original assertation - crank bolts don't need Loctite but they do need lubrication and adequate torque. What happened to all the engineers that used to abound on this forum?

Would you advise, that crank bolts that come from the manfacturer with loctite on their threads, be stripped and lubed?

lks said:

Would you advise, that crank bolts that come from the manfacturer with loctite on their threads, be stripped and lubed?

Yes, if the "mechanic" is going to take pains to ensure correct torque.

lks said:

Guess the aircraft and race car industry is wasting a lot of time and money, using thread locker and safety wire on the millions of bolts and nuts they torque down properly. The bike industry uses thread locker on some bolts, don't they have torque wrenches? Why doe's Campy apply thread locker to the crank bolts that come with their Record carbon cranksets? My $25 a piece titanium after market crank bolts came with thread locker. Ask any mechanic, if he has ever said, " I had to RE-TORQUE it". Of course, most properly torqued nuts and bolts don't come loose. Most, not all.

High frequency vibration can loosen specific nuts/bolts hence campy uses blue threadlock on these ie. bolt at the end of the front derailleur, crank bolts, and alike.

I find it a bit strange that your ti crank bolts came with loctite since ti could seize on steel or al BBs. IMO, titanium grease would be more appropriate (or even grease).

This is just stupid. You can use grease and loctite if you wish! It doesn't matter. Just use some common sense and the crank bolt will be tight. It is not one of those bolts that you can "over tighten". When it is tight it pretty much tells you that. End of story. (Unless your are dumb enought to use an allen wrench that is like 20 inches long, and you put all your body weight on it, then you will break the crank bolt.

And yes, I never had a problem... ever. And I put grease on the bolt sometimes, if I feel like it.

As for putting grease on the spline interface, I don't know about that. I am pretty sure that Aluminum "lubricates" itself when it forms an oxidation layer on its surface. And since the cranks are aluminum, don't see the point for putting grease on the interface. I could be wrong a bit, but still never had any problems.

In other words the crankarm shouldn't get stuck on the bb.

Still, most important thing to remember is that every job is unique and could require something different.

...suitably chastened...

free_rideman said:

This is just stupid. You can use grease and loctite if you wish! It doesn't matter. Just use some common sense and the crank bolt will be tight. It is not one of those bolts that you can "over tighten". When it is tight it pretty much tells you that. End of story. (Unless your are dumb enought to use an allen wrench that is like 20 inches long, and you put all your body weight on it, then you will break the crank bolt.

And yes, I never had a problem... ever. And I put grease on the bolt sometimes, if I feel like it.

As for putting grease on the spline interface, I don't know about that. I am pretty sure that Aluminum "lubricates" itself when it forms an oxidation layer on its surface. And since the cranks are aluminum, don't see the point for putting grease on the interface. I could be wrong a bit, but still never had any problems.

In other words the crankarm shouldn't get stuck on the bb.

Still, most important thing to remember is that every job is unique and could require something different.

I use to be a shade tree mechanic too, until I got my engineering degree and learned it was best to follow the design enginer's directions on the part you are using. It beats guessing or trial and error. Permatex blue thredlocker is a thread lubricant that sets up and becomes a thread locker in 20 minutes. It is good for threads from 6mm to 20mm, that require a holding torque of up to 53lb-ft. Campy uses it on their crank bolts and bottom bracket cups. Campy specifies a crank bolt torque of 28lb-ft. That means you would have to apply 56lb-ft torque to the end/tip of a standard 6" long L allen wrench. Never tried that, because I only use FAA certified torque wrenches. As for what you say you don't know, let me quote Velo New's technical editor. " Greasing the crank axel would allow the the soft aluminum crank to slide too far onto the hard steel or titanium axel and could deform the square hole. With a splined spindle and crank, grease is irrelevent either way.

Good to know that it isn't the best idea to put grease on the connecting interface. Luckly I never did that.

As for the threadlocker and torque wrench, it still doesn't make sense to go through so much trouble. It is just a crankset! Not some rocket or airplane. I never had problems tightening it up, even on square taper cranksets. A crankset shouldn't get loose if tightened. Put some muscle into it.

Sorry about being this anal, but I hate when people make it seem like there is only one way to something.

-Happy riding-

lks said:

Greasing the crank axel would allow the the soft aluminum crank to slide too far onto the hard steel or titanium axel and could deform the square hole.

The square taper problem with grease is interesting- I've always been advised to do it and have always done it. Do you think that it is a problem if the correct crank bolt torque is applied?

artemidorus said:

The square taper problem with grease is interesting- I've always been advised to do it and have always done it. Do you think that it is a problem if the correct crank bolt torque is applied?

I DON"T KNOW., but I will speculate before the end of this post and contact Camagnolo-USA engineering tomorrow, but I expect the factory line will be, degrease it and torque it. Velo New's Technical Editor, Lennard Zinn and the Campy web site, say the same thing. "Before you assemble the cranks on the bottom bracket axel, degrease the axel and square heads thoroughly. NEVER lubricate the bolts before tightening them". Lennard"s book came out in 2000, before carbon cranksets. The Campy web site instructions are dated 2005, when the carbon crankset option was introduced, but the instructions don't differentiate between carbon an alloy. I would think there were plenty of failures, or they wouldnt have written these instructions. I would speculate the failure mode was a stress fracture, where one of the crank arm square holes was deformed. Probably on the inside of the crank square hole where the most axel taper is. It could be duplicated by greasing the axel and tightning the bolt until failure occured, and recording what torque it happened at. If Campy Italy knows what torque that is, I doubt they would tell me. Seems like there are two choices, if it ain't broke, don't fix it. Or pull it apart, degrease it and check for hairline fractures. If non, assemble and torque to appropriate spec. I have what is considered the, price is no object, best bottom bracket in the world. A Phil Wood all Titanium. I quote from the installation instructions."Clean and lightly oil the ends of the spindle, the square holes in the crankarms, and the crankarm mounting bolts". Even the mounting rings are Titanium (optional), but loctite is provided for them. I can only speculate, that the spindle taper is not enough to deform the square crankarm hole, with oil applied. To complicate things, I use after market Titanium mounting bolts. I use a special anti seize compound for this Ti to Ti application.

Manufacturers and assemblers have to make the best of their situation. Once it leaves them, that’s it, they don’t really know where its going and this is why they sometimes use locking compounds. They have to make the best of the situation.

Ideally there will be follow-up maintenance and servicing carried out by people who know what they are doing. Things like crank bolts particularly on new bikes always need to be checked and retightened. I recommend the use of Never-Seize on re-assembly of crank bolts and splines together with occasional checking particularly when new. One should NEVER assemble anything without lubrication or in certain cases an appropriate locking compound.

Both Octa-link and ISIS drives are very good systems and are trouble free if correctly assembled and maintained. Clearly this has not been done on the bike in question here.

Locking and wiring etc. are widely used in motor sport and aviation for good reasons. Bicycles however are not subject to anything like the loads, temperatures and conditions that aircraft etc. are and so in most cases a bit of common sense and a regular checkup is all that’s needed.

Jay…. who has 30+ years in aviation, automotive engineering and manufacturing and 40 years of cycle maintenance to draw on and hasn’t lost a crank yet… touch wood.

otherworld said:

Manufacturers and assemblers have to make the best of their situation. Once it leaves them, that’s it, they don’t really know where its going and this is why they sometimes use locking compounds. They have to make the best of the situation.

Ideally there will be follow-up maintenance and servicing carried out by people who know what they are doing. Things like crank bolts particularly on new bikes always need to be checked and retightened. I recommend the use of Never-Seize on re-assembly of crank bolts and splines together with occasional checking particularly when new. One should NEVER assemble anything without lubrication or in certain cases an appropriate locking compound.

Both Octa-link and ISIS drives are very good systems and are trouble free if correctly assembled and maintained. Clearly this has not been done on the bike in question here.

Locking and wiring etc. are widely used in motor sport and aviation for good reasons. Bicycles however are not subject to anything like the loads, temperatures and conditions that aircraft etc. are and so in most cases a bit of common sense and a regular checkup is all that’s needed.

Jay…. who has 30+ years in aviation, automotive engineering and manufacturing and 40 years of cycle maintenance to draw on and hasn’t lost a crank yet… touch wood.

Never say never. Campy can void the owners warranty, if they find lube, anti-seize, ect. on the bottom bracket square axel, crankset square hole & bolts. Better clean everything off those parts, before you ever send them them, damaged, back to Campy. They didn't print those instructions, to be ignored.