Bicycle Mechanics - No grease at all on crank or spindle?

Was reading a how-to on the drivetrain. This book said when assembling the crank arms back on the spindle, to DO NOT put any grease on the square spindle and matching crank recess.

Why is this? I generally like to put a very light coat on metal surfaces just for corrosion protection.

Thanks..knotty

It's a debatable subject. My experience has been that a a light coating of grease isn't going to hurt anything, and it gives me some peace of mind. I lightly coat the tapered ends of the spindle, and grease the threads. The most important thing is to put the cranks on plenty tight.

For splined interfaces (ISIS, Octalink), it's recommended that you grease the splines before installing.

I put a thin coat on mine as I think it helps seat them all the way and gets the rings closer to the bb shell. I read some brands of square taper should not be greased and instructions should be included if grease isnt to be used. Mine Sugino XD-300 came with no instructions so I greased them slightly.

Grease should lubricate the surfaces enough to allow small irregularities to be overcome, allowing a tighter fit. That in turn should mean less risk of premature interface wear.

Ah, the great greased spindle debate. As I recall, the general BikeForums breakdown is around 70% grease / 30% no grease. I'm in the grease column.

OK, that makes me feel better... I'll just leave the coating of grease I originally put on...LOL

knotty

For their square taper cranks/bottom brackets Campagnolo, for reasons no one seems to understand, says absolutely no grease while Shimano doesn't specify either way.

However, a mechanical engineer and very good bike mechanic I know says grease should always be used for this type of interface.

put a bit of grease on, then wipe it off with your fingers

I always apply grease to the spindle. I prevents corrosion and that unwanted creaking noise. Better to do it now then to have to take apart your crank after you have put it together.

I usually grease mine lightly. I feel it makes them slide on tighter, and may help it overcome any "snags" (irregularities on the tapered surfaces. Theoretically this prevents ovalization which would occur if it was only installed partially. BUT it can also lead to over tightning and consequential cracking of aluminum cranks (usually happens at the corner of the spindle hole, and is hard to see if it's clean), as it is easier to overtighten when grease is used, than when not used. I then put a drop of loc-tite onto the crank bolt to prevent loosening of the greased crank arms.

I I've only used the early shimano hollowtech splined (octalink) for which I think it's nigh impossible to overtighten. So grease away and crank on it (pun intended) if that's what you have, as you need to "hit bottom" while tightening. If you have another style, I can't say for sure.

The theory I've heard is that you run the risk of allowing the square taper to push too far into the crank spreading it out enough that the crank no longer interfaces properly with the BB spindle. That being said I've never seen this happen in my 5 years of wrenching even on some pretty damn greasy looking crank/bb assemblies. Given my unfortunate experiences with galvanic corrosion (an aluminium seat post that was completely bonded to the inside of a steel frame) I'd say that a very slight coat of grease is probably a good idea.

BUT it can also lead to over tightning and consequential cracking of aluminum cranks (usually happens at the corner of the spindle hole, and is hard to see if it's clean), as it is easier to overtighten when grease is used, than when not used.

This is the only reason I could think of. The spindle being a wedge, can exert some large forces outward on the crank recess.

knotty

Well I am sure my thinking is all wrong here, but after numerous attempts to keep the crank tight on my old Rock Hopper I greased the square spindle hoping the crank would seat better, and used lock tight on the threads hoping to keep it there. So far so good...

It seems to me that there wouldn't be any difference between a light coating of grease or a heavy coating. If there is grease on the interface than the result is the same either way.

It seems to me that there wouldn't be any difference between a light coating of grease or a heavy coating. If there is grease on the interface than the result is the same either way.
Correct. A heavy coat of grease becomes a light coat of grease under pressure.

i vote grease

reasons all posted above

Assuming that the no grease spec is similar to the dry/lubed torque spec differences on bolts, one might have to lower the torque spec on the crank bolt to obtain the same position of the crank on the square taper spindle. If the same torque is used, it is likely that the crank will be on the spindle with more force than it would have been if dry.
This is probably moot in the workaday world as most people will install the cranks until "tight enough" anyway.
Greasing splined cranks is appropriate because they bottom out against a flange.
If your not breaking cranks and your not deforming tapered spindles than grease or not as your choice.

For their square taper cranks/bottom brackets Campagnolo, for reasons no one seems to understand, says absolutely no grease while Shimano doesn't specify either way.

However, a mechanical engineer and very good bike mechanic I know says grease should always be used for this type of interface.

I don't quite understand Campagnolo's reasoning, which means I do what I want. I always lube metal-to-metal interfaces just out of principle I guess. Never had an issue with Campagnolo cranks.

I don't quite understand Campagnolo's reasoning, which means I do what I want. I always lube metal-to-metal interfaces just out of principle I guess. Never had an issue with Campagnolo cranks.

I read someplace using grease wehn no wanted by the designer can cause the crank to be pressed on too far onto the spindle and further than what the design calls for.

maddmaxx hit a hole in one!

That is the exact reason why lubing the tapered spindle is not recommended.
Unlike the clamping forces of a steel frame tube and Al seatpost, The angle of the spindle and mating Al surface of the crank arm is similar to the mating and friction anchoring of V-shaped threads.
By lubing, the friction is overcome and the torque specified can't be obtained accurately. You've now over-torqued the interface actually. And since they are dissimilar metals, Al being softer, it deforms slightly, and with repeated application, the crank arms are ruined.

This has also been an hot debate in automotive fasteners forums. Anal German engineers stand by dry bolting.
While those living in harsh environments that corrode everything, think it's necessary to apply anti-seize.

IMHO, if the spindle is not bare steel, meaning it's surface treated (ie. black oxide, nickel plated), and the Al crank arm is anodized, then the two shouldn't seize together, no lube is necessary.
I've had lubed square tapered spindles in the past with a thin coat of oil, but I've also witnessed some deformed crank arms on some friends' bikes.

Campagnolo's spindle is slightly longer and shallower in angle if I'm not mistaken. Shallower angle would make it easier to deform the Al than a steeper one.
Maybe that's why they advise no lubes.

I don't quite understand Campagnolo's reasoning, which means I do what I want. I always lube metal-to-metal interfaces just out of principle I guess. Never had an issue with Campagnolo cranks.

Doing something just because, without knowing the reason why one should do it is never good to follow.

maddmaxx hit a hole in one!

Campagnolo's spindle is slightly longer and shallower in angle if I'm not mistaken. Shallower angle would make it easier to deform the Al than a steeper one.
Maybe that's why they advise no lubes.


At the risk of diverting too far from the thread, I believe the angle statment above is incorrect. See Sheldon Brown's article on this at http://sheldonbrown.com/harris/bottombrackets.html. Click the "Not sure what size you need?" link; then click the ISO v. JIS link.

Getting back to the thread, I've always greased spindles, and have never had a crank fail.

I read someplace using grease wehn no wanted by the designer can cause the crank to be pressed on too far onto the spindle and further than what the design calls for.

I have read that too. I just have this thing about dry metal against dry metal. Maybe it is all those years of prying apart corroded parts, I don't know. In any case, I reckon I have been lucky as to not deform any crank arms.

Thought I'd better update this. Been experimenting since I posted this. With greased spindle, I tightened the bolts and rode a couple times. Checked the bolts and they were amazingly loose so tightened them and rode again. After a couple rides, the bolts were very loose again.

Took the crank arms off and wiped the grease off the crank recess and spindle and followed with a solvent rag to make sure it's all gone.

Put the cranks back on and tightened the bolts. Checked the bolts after riding. They were very slightly loose than the original tightening but nowhere as loose as when greased and has not loosened since after many rides.

Not exactly scientific but thought I'd pass my experience on.

knotty

If your bolts are coming that loose after riding a couple of times, you're either not tightening them enough, or you're a really X-TREME rider.

As a counterpoint, I hadn't been greasing the spindles (on recommendation) and a creak keeps coming back bit by bit. I suspect a little clean-clean and a little grease-grease will get me right.

Doing something just because, without knowing the reason why one should do it is never good to follow.

Huh? It makes more sense to me to always follow the rules unless I have a good reason not to.

In the case in point, I have seen a few crankarms that were cracked at the mounting hole. I assume the crack could have been caused by forcing the crank arm too far onto the taper.

No, no, no grease on square taper spindles. Don't know where I got that advice originally, but I've followed it for 30 years without problems. Yes to grease/anti-seize with ISIS spindles, of course.

NO GREASE!!! I've been a mechanic in the past and ALL of the best mechanics I've met, including those who worked "pro" teams with giro experience, do their bbs with square tapers with NO GREASE, many including myself go as far as to clean the tapers and crank "holes" with Acetone to remove incidental grease particles/contamination b4 installing. I've worked on too many bikes that had grease on the tapers that had derformed/expanded the crankarms so much they had to be replaced; they wouldn't- stay on, stay "fixed", ruined the chain line (that affects shifting) etc.. It' not that hard to overtighten a crankarm, especially with less than high quality materials. It's best to use a torque wrench or short handled wrench and re-torque after apx 100 miles

Thanks pat5319, JanMM, I cleaned the spindle and crankarm hole with brake cleaner and torqued the bolt to 22-24 FP.

knotty

I'm in a completely different industry, think engines and transmissions, and we never ever ever lube tapers. I will admit to all of ours being round rather than square tapers, but sure have seen a lot of ruined parts due to being lubed during assembly.

Just my .02

I'm in a completely different industry, think engines and transmissions, and we never ever ever lube tapers. I will admit to all of ours being round rather than square tapers, but sure have seen a lot of ruined parts due to being lubed during assembly.

Just my .02

Appreciate your 2 cents. How about using 'assembly lube'?

Appreciate your 2 cents. How about using 'assembly lube'?

Tapers must be clean and dry per OEM specs.



In my industry.

I've heard from very well-informed sources that adding lube to screws reduces the required torque to get the screws properly seated. In my business, we've had problems with robotically screwed in (stainless) screws stripping the (aluminum) holes when a lube was added to the screws. The solution was to reduce the torque spec on the robotic screw drivers if lubed screws were used vs non-lubed.

Based on this, I'd say you can grease your spindles if you want but I would be careful about the amount of torque applied to the crank bolts. If you use the mfg recommended torque values I'd follow their instructions about dry vs greased spindles as well.