Proper procedure for square taper BB
#26
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I used to use grease, following the Jobst Brandt argument.
However nowadays I use thick chain oil instead, serves the same purpose for anti-galling during the install and avoids starting arguments with the other mechanics in the shop.
and no locktite, plenty of grease on those threads though.
However nowadays I use thick chain oil instead, serves the same purpose for anti-galling during the install and avoids starting arguments with the other mechanics in the shop.
and no locktite, plenty of grease on those threads though.
#27
Senior Member
I don't think it's the end of the world if someone installs a crankarm on a slightly oiled taper. But grease or anti-seize just isn't the tool for the job. IMPO
#29
Senior Member
It doesn't reach the bearing grease - there's about 1+ cm of axle between them. Of course it should never mix with other greases, especially inside the bearings. It is put on the axle part where the cranks are placed, nowhere near the bearings. Dirt and water are a lot more likely to contaminate the bearings, than the mounting paste - especially if the excess is wiped off after mounting (as it should).
Like I said, even if it does reach the bearing, it's not going to damage anything. It's just oil with some very soft sacrificial materials in it like copper and zinc oxide. Neither of those will do any damage to a bearing or race.
Either choice has possible downsides. Yes, a dry taper can gall. Yes, a "wet" taper can be overtightened. IMPE the latter is more common and has worse consequences than the former. And I've worked on a LOT of very old bikes in my time. I've never not been able to extract a crankarm from a dry taper. Ever. Given, of course, intact extractor threads. Sometimes a minute with a propane torch is all it needs to come off.
OTOH I've seen more than a few crankarms pushed on so far that they are not usable. In most cases, they were greased.
A deft trained touch, or a torque wrench, will usually prevent overtightening. But there are far more people in the "tighter is better" club than have either of those things.
The only time I could see using anti-seize on a taper is for a bike that will see extremely wet and salty conditions. Even in that case, you'll probably be chewing through BBs often enough that galling won't be a problem.
FWIW, Barnett's recommends dry tapers. It's not the Bible, but it's the Book.
Let's keep religion out of this, ok?
#31
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I've done both over the years. But I have stopped greasing the tapers and if chainline is important (and esp if I do not want the cranks creeping in further) I clean the tapers with solvent. I have observed that greased tapers lead to the crank moving inboard after enough re-mounts to the point where I have to start using longer spindles or shimming the tapers. I have even split a crank.
Now I have a bike set up where I want the chainrings as far inboard as possible to best line up with track hub cogs. So I am using a Phil Wood BB to dial in the chainline so the ring doesn't quite scrape the chainstay paint. I want everything to stay right there. Really dry fits only on that bike.
Like others above, I have never had issues getting the cranks off. And I have never seen evidence of galling in 50 years. So I see little plus to using grease/oil/anti-seize. Just downside; the slow demise of of the crank's tapers. Not an issue if you never re-install the cranks.
Ben
Now I have a bike set up where I want the chainrings as far inboard as possible to best line up with track hub cogs. So I am using a Phil Wood BB to dial in the chainline so the ring doesn't quite scrape the chainstay paint. I want everything to stay right there. Really dry fits only on that bike.
Like others above, I have never had issues getting the cranks off. And I have never seen evidence of galling in 50 years. So I see little plus to using grease/oil/anti-seize. Just downside; the slow demise of of the crank's tapers. Not an issue if you never re-install the cranks.
Ben
#32
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Of course.
Like I said, even if it does reach the bearing, it's not going to damage anything. It's just oil with some very soft sacrificial materials in it like copper and zinc oxide. Neither of those will do any damage to a bearing or race.
My argument is not that it "hinders the engagement." It's that it is rarely necessary, and more often can lead to overtightening.
Like I said, even if it does reach the bearing, it's not going to damage anything. It's just oil with some very soft sacrificial materials in it like copper and zinc oxide. Neither of those will do any damage to a bearing or race.
My argument is not that it "hinders the engagement." It's that it is rarely necessary, and more often can lead to overtightening.
Torquing it without lube on the interface, on the other hand, does cause problems, as was nicely explained in the link from Sheldon Brown's site.
Shimano cartridge square taper BBs last surprisingly long, even with salty winter roads. I've been very happy, even with the "lower middle end" models.
#33
Senior Member
This is incorrect. Lubricant will allow a proper crank to axle engagement using appropriate bolt torque. It will not help overtightening. I mean - you can overtighten and strip bolts if not paying attention, of course, but having a crank to axle interface lubed won't make any difference there.
A lubricated bolt will gall and seize up if not lubricated and overtorqued. So yes, always anti-seize your bolts. But you'll almost certainly either bottom out the crankarm or the bolt itself, or crack the crankarm before you strip the threads on a crank axle, bolt, or nut from overtightening it. I'm sure it's happened, not that I've tried.
In this case, as I was implying before, it's not about right or wrong. It's about tradeoffs. When manufacturers and bicycle service institutes make recommendations, I think it's fair to say they've weighed the options and done their testing, engineering, and reverse-engineering, and don't make those recommendations because someone BITD told them that's how it's done. Their collective experience is considerable, and well earned.
#35
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First, if a bolt is not going to be torqued anywhere near its maximum, then it's highly unlikely it will gall. That is the case with crank bolts. Torque values tend to be around 60-70% of yield strength. Campagnolo's torque spec is in line with general torque values for 8mm dry bolts.
Second, A dry bolt is less likely to loosen than a lubed one if under-torqued, because of friction. (BTW tapered fits maintain their hold through friction, so this is also an argument for dry tapers.) Bolts also maintain their hold by being in tension, and an under-torqued bolt might not have enough tension to stay secure.
A dry bolt is also less likely to be over-torqued. So maybe their recommendation is to build in a margin of safety against both those problems.
To that point: Torque values for lubricated bolts are 10% lower than dry because there is less friction. So if you want to lube your Campagnolo crank bolts, you can, but reduce that torque by the 10% so you don't overdo it. If you want to lube your tapers, you can, but reduce the torque even more to keep from over-installing the crankarms.
Or you can just follow Campagnolo's recommendations. It really is about manufacturer recommendations when it comes to such things. Some bolts are tightened to a torque spec, whether dry or lubed. Some are tightened to snug, then clocked an additional fraction of a turn. (This is the best way to keep from over-tightening pedals, BTW. Take them 1/16 turn past snug. No more is necessary.)
The square taper crank has been around for about 80 years. Campy's been making them for about 60 years. Engineers generally have this stuff figured out. So if you deviate from their recommendations, you should have some idea of how to compensate.
Different materials also require different torque values. If you use titanium crank bolts, they will have a much different torque spec than an 8.8 steel bolt. Much lower, in fact, about a third of 8.8 steel. (Which is why you should tighten the cranks on the taper with a steel bolt, then remove the steel bolt, and then put on the titanium.)
#36
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The way to push the cranks too far is to put them on dry. They will get a bit (more) damage in the process. Then ride a bit, let the fretting do it's thing. Then re-tighten the bolts. And repeat that several times. Finally, the cranks will be pushed too far, resulting in a split crank interface if you go far enough.
You can do that even with lubed ones, of course. Just keep riding-re-tightening the bolts.
In this case, as I was implying before, it's not about right or wrong. It's about tradeoffs. When manufacturers and bicycle service institutes make recommendations, I think it's fair to say they've weighed the options and done their testing, engineering, and reverse-engineering, and don't make those recommendations because someone BITD told them that's how it's done. Their collective experience is considerable, and well earned.
I have quite strong hands. Never have I been able to tighten the bolts so that the cranks are split in one go, or they "climb" too high. Lubed, or not. So, at least mine, experience confirms what I've said. Could it all be wrong? I guess it's possible. Only after 20 more years could I claim my experience to have any sort of statistically valid value - it's about big numbers. Also, if I find/hear an explanation explaining the "opposing" (dry mount) theory that holds water, I'd be happy I've learned something new and correct my views and practice.
Off topic: about 9 years old, overhauling an old lawnmower with my father. He told me to tighten some (rather large) bolts. I asked how tight? He said "as tight as you can". Considering the tool I'm using is not a long lever and I'm a kid, so he'd probably have to check and re-tighten the bolts. I had stripped the first one, realized it and let him know, before doing any more damage. He just laughed and couldn't believe. "I underestimated you, it's my fault". Afterwords he would always joke about it when we worked on something: "tighten with small force, you know, NOT stripping the bolts..."
@gearbasher I have the manual in the shop. Was "delighted" with the instructions. That, and the right hand thread on the right side of bottom brackets are the jewels of Italian engineering IMO. Though I'm yet to test the infamous Campagnolo delta brakes.
Nothing against Campagnolo, really, love their brifters, love how they made the whole system shift nicely (Shimano got it right in 2nd go with 10 speed, and with 11 speed road), and the design is lovely as well.
Last edited by Bike Gremlin; 02-08-18 at 12:53 AM.
#37
Senior Member
@gearbasher I have the manual in the shop. Was "delighted" with the instructions. That, and the right hand thread on the right side of bottom brackets are the jewels of Italian engineering IMO. Though I'm yet to test the infamous Campagnolo delta brakes.
Nothing against Campagnolo, really, love their brifters, love how they made the whole system shift nicely (Shimano got it right in 2nd go with 10 speed, and with 11 speed road), and the design is lovely as well.
Nothing against Campagnolo, really, love their brifters, love how they made the whole system shift nicely (Shimano got it right in 2nd go with 10 speed, and with 11 speed road), and the design is lovely as well.
#38
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I agree. I don't use a torque wrench but still remind myself to not be a "gorilla" and tighten the crap out of the crank bolt. One technique might be to tighten with an open hand. When you palm starts to hurt, then its tight enough.
#39
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I've been riding only Campagnolo equipped Italian steel frames since the early '80s. My BB method is: grease on the threads of the cups, dry tapers, one drop of blue locktite on the crank bolts and everything torqued to Campy's specs. I've never had a cup unscrew or a crank arm come loose. Let me add, I have a C-Record era Chorus crankset that has over 70,000 miles on it and is still in use.
Are you a heavy rider?
I still see no benefits in mounting them dry. Just (potential) problems. Why they wrote such manual is beyond me, really.
Last edited by Bike Gremlin; 02-08-18 at 08:35 AM.
#40
Installing Cranks by Jobst Brandt
#41
Senior Member
Campy also recommends putting their sealed bearing, square taper BB cups in dry. They come new with some yellow looking compound on them. I tried them dry and after a few hundred miles they start to creak. So, that's one Campy recommendation I don't follow.
#42
Senior Member
This also won't happen. Don't take my word for it. If you have an old set, try doing it in one go. Lube it with any lube and try pushing it too far. Bolt will strip first.
The way to push the cranks too far is to put them on dry. They will get a bit (more) damage in the process. Then ride a bit, let the fretting do it's thing. Then re-tighten the bolts. And repeat that several times. Finally, the cranks will be pushed too far, resulting in a split crank interface if you go far enough.
You can do that even with lubed ones, of course. Just keep riding-re-tightening the bolts.
The way to push the cranks too far is to put them on dry. They will get a bit (more) damage in the process. Then ride a bit, let the fretting do it's thing. Then re-tighten the bolts. And repeat that several times. Finally, the cranks will be pushed too far, resulting in a split crank interface if you go far enough.
You can do that even with lubed ones, of course. Just keep riding-re-tightening the bolts.
In your opinion, dry tapers make this more likely. I don't want to speak for Campagnolo and Barnett's, but seems in their opinion, they make it less likely. Since you admit it can happen either way, I'm going with them. No disrespect intended.
As I acknowledged, potential problems either way. The "benefit" is fewer long-term risks. Risk mitigation is playing the percentages.
I would say there is a sweet spot in the middle where it probably doesn't matter whether you grease or not. If you understand the risks and use the correct tools and torques, and adjust intelligently for your personal preference, things will probably be fine. How many home mechanics have either the tools or the knowledge? For that matter, how many shops do? That's why there are resources provided by manufacturers, and knowledge-gathering and instructional institutions like Sutherland's and Barnett's and UBI. Whether you choose to believe them or someone else like Jobst Brandt, well, that's a religious decision I suppose.
In the hands of a ham-fisted mechanic, whether professional or home, all bets are kind of off.
You said it, not me.
#43
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Thread Starter
If you properly torqued the arms don't retorque. The arms will climb up the taper slightly each time you torque the bolts until you may crack the arms.
Installing Cranks by Jobst Brandt
Installing Cranks by Jobst Brandt
Yeah I believe Sheldon said the same thing.
#44
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I would say there is a sweet spot in the middle where it probably doesn't matter whether you grease or not. If you understand the risks and use the correct tools and torques, and adjust intelligently for your personal preference, things will probably be fine. How many home mechanics have either the tools or the knowledge? For that matter, how many shops do? That's why there are resources provided by manufacturers, and knowledge-gathering and instructional institutions like Sutherland's and Barnett's and UBI. Whether you choose to believe them or someone else like Jobst Brandt, well, that's a religious decision I suppose.
Last edited by Bike Gremlin; 02-09-18 at 02:49 AM.
#45
Senior Member
Fretting damage can happen either way, but dry mounting makes it worse, with some (more) damage happening during the mounting process if mounted dry. Not putting much torque on the cranks does help as well. Heavy, strong rider that prefers mashing is more likely to suffer from improperly mounted cranks.
By the way, the bolt does not hold the crank on. It presses it on, but after that it serves to keep it from coming off. How? By preventing repeated relative motion.
This is easily verified experimentally.
This is not true. Try it on some old BB. Lube, and try overtightening the crank. See if the bolts threads strip first, or the crank moves too high up/splits. Your claim that lubing helps the "overtightening" is simply misinformed IMO. Could I be wrong? Possibly, but I'm yet to find theoretical, or practical evidence against lubing and/or towards dry mounting.
I claim that lubing tapers more easily enables overtightening of the crank (among other things.) Repeated overtightening eventually causes deformation of the taper hole in the crank. Repeated deformation eventually causes the crank to either bottom out on the cup, the bolt to bottom out on the spindle, or the crank to crack.
IMPE, the most common of these by far is for the bolt to bottom on the spindle. The other two are relatively rare. But I have seen both.
I am NOT claiming that lubing the tapers lets you overtighten the crank to failure in one go. You keep arguing against something I never wrote.
If their instructions don't make sense to you, the problem might not be with the instructions.
I don't think I'm the one being "religious". Religious would be holding a written book as gospel, without questioning it. I've tried various methods, read various opinions and books and came to some conclusions. Still being open to corrections. However, like I've said, so far I'm with the "lube first" method.
You just quoted me saying basically, "if it's done with wisdom and experience, it probably doesn't matter whether you grease or not." What about that idea sounds religious to you? Again, I'm not sure you're actually reading what I wrote.
I'm happy to continue this, but only if you read, and respond to, and argue against, things I am actually writing. Thanks for the fun.
#46
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No, not friction. The preload high enough to prevent movement even with some elastic deformation from pedaling torque is required to minimize fretting and the interface damage, cranks coming loose etc.
It does happen, due to elastic deformation and motion of metals. Grease reduces the effect, mounting paste even more so IMO.
Yes, the bolt prevents the crank from sliding off.
This is not correct IMO, but I see no point in going round in circles.
And have failed to make corrections. One example is the pedal to crank interface being kept flat, instead of tapered, which also allows fretting damage and requires left hand thread on the left pedal to prevent it from loosening through use.
Could be, but I don't think so.
Campagnolo didn't just make cranks and ship them off and never think about them again. They have for 60 years provided racers and racing teams with them, and also race support. They have experience with their products from production to the end of their service life. They've seen the mistakes and the failures along with the successes. They have big numbers.
Could be, but I don't think so.
#47
Senior Member
I'm not saying fretting doesn't happen, nor am I saying fretting is OK. I'm saying the risk of damage from fretting is relatively less significant than the risk of other types of damage that a dry taper helps mitigate.
Yes, there is some elastic deformation of course, but it's manageable; that's what torque values are for, for both the fastener and the taper fit. It's the plastic kind I'm concerned about, which reducing friction increases the risk of by requiring different (lower) torque values that are usually not followed if they are even known.
Glad that is settled, at least!
That would be a handy solution, but this is hardly Campagnolo's fault. Pedals have been made that way since forever, so everyone who's ever made a pedal has failed to do this. Probably because it's not such a big deal if you don't overtighten them. (Not to start on another topic, but pedal overtightening is another pet peeve of mine.)
#49
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#50
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I'm not saying fretting doesn't happen, nor am I saying fretting is OK. I'm saying the risk of damage from fretting is relatively less significant than the risk of other types of damage that a dry taper helps mitigate.
Sure, grease does reduce friction. No argument there. Whether that's a good thing or not is the question, isn't it?
Sure, grease does reduce friction. No argument there. Whether that's a good thing or not is the question, isn't it?
Yes, there is some elastic deformation of course, but it's manageable; that's what torque values are for, for both the fastener and the taper fit. It's the plastic kind I'm concerned about, which reducing friction increases the risk of by requiring different (lower) torque values that are usually not followed if they are even known.
Glad that is settled, at least!
That's what we bicyclists do, isn't it? We almost always end up back where we started.
That would be a handy solution, but this is hardly Campagnolo's fault. Pedals have been made that way since forever, so everyone who's ever made a pedal has failed to do this. Probably because it's not such a big deal if you don't overtighten them. (Not to start on another topic, but pedal overtightening is another pet peeve of mine.)
That's what we bicyclists do, isn't it? We almost always end up back where we started.
That would be a handy solution, but this is hardly Campagnolo's fault. Pedals have been made that way since forever, so everyone who's ever made a pedal has failed to do this. Probably because it's not such a big deal if you don't overtighten them. (Not to start on another topic, but pedal overtightening is another pet peeve of mine.)