Creaking crank...

iregk

Any ideas here. Could this be as simple as a quick tightening?

This evening late on in my spin a creaking sound from the crank started to emerge. Its worst when standing and only happening when pushing with the left foot. Kinda like an ewwwruuugh type sound, if you can imagine that. Actually even heard that sound when trying to loosen a very tight bold. Its like that.

Testing it out if I stand up and push back with my left foot it happens, pushing down forward it happens. Doesn't when spinning only when putting some pressure through the crank. I got off to check it and when I put the left crank arm upwards and pull it in towards the seat bar it moves inwards slightly. Can't quite recall if its supposed to have a slight bit of give in it.

Any clues?

kona

iregk wrote: »

Any ideas here. Could this be as simple as a quick tightening?

This evening late on in my spin a creaking sound from the crank started to emerge. Its worst when standing and only happening when pushing with the left foot. Kinda like an ewwwruuugh type sound, if you can imagine that. Actually even heard that sound when trying to loosen a very tight bold. Its like that.

Testing it out if I stand up and push back with my left foot it happens, pushing down forward it happens. Doesn't when spinning only when putting some pressure through the crank. I got off to check it and when I put the left crank arm upwards and pull it in towards the seat bar it moves inwards slightly. Can't quite recall if its supposed to have a slight bit of give in it.

Any clues?

Its Crank bolt isnt torqued right. DOnt ride it until you tighten it to 45 Nm (presuming its a Tapered crank)

jayjbe

just in case everything is tight and there is still play...depending on the BB type try packing with some grease and retightening. some BB's spec's can be slightly off.

gman2k

I was out doing a bit of MTB last night, there was a funny noise going on, next thing my left crank came off!!!
Bit of a trail fix and going again a few minutes later!

iregk

Thanks Kona. I'll take it to the store tomorrow evening as I've no torque tools so can't be guaranteed how tight is enough.

seamus

As Kona says, if your crank wobbles at all on the axle, then stop riding immediately or you're about five minutes away from needing a new crankset.

doozerie

If it is a square taper axle then also consider greasing the axle tapers before fitting the cranks. Some people believe that to be a recipe for disaster, but personally I find the argument in favour of greasing convincing. A torque wrench is very useful too, advisable even.

I think that greasing the likes of ISIS splines is a lot less controversial and that the manufacturers themselves actually recommend it.

kona

doozerie wrote: »

If it is a square taper axle then also consider greasing the axle tapers before fitting the cranks. Some people believe that to be a recipe for disaster, but personally I find the argument in favour of greasing convincing. A torque wrench is very useful too, advisable even.

I find that article to be a disjointed load of waffle. Hes trying to say that the right hand crank doesnt transmit torque to the Bottom bracket?.

What is Torque?

If it didnt transmit torque, the BB wouldnt turn when the RH crank is turned. Bending moments are a different story altogether and is something that youd need to analyse in a lab.

His argument for fretting is alot of **** too, If you want to avoid this you would lap the Tapered crank onto the BB axle.

Also since its a interference fit, perhaps he should go measure exactley what the interference fit is on a tapered crank, Id imagine if the BB or the Crank are outside tolerance this would attribute to splitting of AL cranks, Id also question the wisdom of using a Tapered fit for for a AL crank onto a carbon steel BB.

FWIW I grease my tapers too, however I used the same Theory on a Tapered flywheel. A year later it took a blow torch and some serious pulling to get it off (I had a 6 ft lever on it and i was swinging off it). Id be inclined to say lapping the parts on is more beneficial than greasing.

apoeiguq3094y

kona wrote: »

I find that article to be a disjointed load of waffle. Hes trying to say that the right hand crank doesnt transmit torque to the Bottom bracket?.

What is Torque?

If it didnt transmit torque, the BB wouldnt turn when the RH crank is turned. Bending moments are a different story altogether and is something that youd need to analyse in a lab.

When you push down on the left crank, the torque or "turning force" goes through the axle (supported by the BB) to the right crank and chain ring. The chain ring is attached to the right crank. Torque applied by the left crank, is resisted by the chain pulling on the chain ring.

When you push the right crank, the torque is applied directly to the chain ring. there is no torque being applied through the axle as the chain ring and crank are on the same side.

kona wrote: »

His argument for fretting is alot of **** too, If you want to avoid this you would lap the Tapered crank onto the BB axle.

Also since its a interference fit, perhaps he should go measure exactley what the interference fit is on a tapered crank, Id imagine if the BB or the Crank are outside tolerance this would attribute to splitting of AL cranks, Id also question the wisdom of using a Tapered fit for for a AL crank onto a carbon steel BB.

FWIW I grease my tapers too, however I used the same Theory on a Tapered flywheel. A year later it took a blow torch and some serious pulling to get it off (I had a 6 ft lever on it and i was swinging off it). Id be inclined to say lapping the parts on is more beneficial than greasing.

The interference changes depending on how much you tighten the crank bolt. When you are tightening the bolt you are overcoming the friction of pushing the crank up on the taper, and also deforming the metal in the crank and taper. The tightening torque specified will give a certain about off preload for the crank on the taper, so that when the load comes there won't be a gap between the crank and the taper.

If you don't know what the friction you have to overcome is, you can't know how much of a preload is on the crank&taper. By lubricating it, its always going to be the same. Thats the advantage of lubricating. You could achieve the same effect without lube by over-torquing the bolt, but you wouldn't know how much to over-torque by.

kona

apoeiguq3094y wrote: »

The interference changes depending on how much you tighten the crank bolt. When you are tightening the bolt you are overcoming the friction of pushing the crank up on the taper, and also deforming the metal in the crank and taper. The tightening torque specified will give a certain about off preload for the crank on the taper, so that when the load comes there won't be a gap between the crank and the taper.

If you don't know what the friction you have to overcome is, you can't know how much of a preload is on the crank&taper. By lubricating it, its always going to be the same. Thats the advantage of lubricating. You could achieve the same effect without lube by over-torquing the bolt, but you wouldn't know how much to over-torque by.

The Interference will change to a point and then even out. The BB axle isnt shaped like a cone. If you tighten to 45Nm, thats the force needed to engage the interference fit. Its obviously goig to be quite small, a few thou. At this rate by using lube your either going to :

Reduce the Interference fit due to a layer or grease between the Crank and Taper.

Push the lube out the back of the crank.

By lapping the parts on you will reduce the friction and remove the need for lube. It comes back to tolerances and the quality of the finish on the parts. The whole point of a Interference fit is friction, I cant see how lubricating it will reduce the friction to the point of it having an effect. I wonder if there are any actual tests done on this.

TBH A crank isnt going to fall off if you don't lube the taper. It will fall off if its not tightened correctley, and this applies to the R/H crank too.

Im nearly convincing myself to stop lubing cranks. It does stop mysterious creaks the odd time though.

apoeiguq3094y

kona wrote: »

The Interference will change to a point and then even out. The BB axle isnt shaped like a cone.

the square end is tapered i know its not round, but the width of the square gets bigger as you go further in on the axle.

kona wrote: »

Reduce the Interference fit due to a layer or grease between the Crank and Taper.

The grease isn't going to reduce the interference, it just smooths out the surface. if anything it would increase the interference.

kona wrote: »

The whole point of a Interference fit is friction, I cant see how lubricating it will reduce the friction to the point of it having an effect. I wonder if there are any actual tests done on this.

The whole point of the interference isn't friction, its preload. The interference introduces a strain that has to be overcome before a gap will appear between the 2 components. its the same idea as prestressing concrete to stop crack growth. by placing the concrete in compression, you make it very hard for a crack to form on the surface. Same applies here. If you had no preload from the interference, when you turned the crank, a small gap would appear between the axle and crank in some locations. by introducing a preload, this means that the preload must be overcome before the gap appears.

kona wrote: »

I wonder if there are any actual tests done on this. ....
TBH A crank isnt going to fall off if you don't lube the taper. It will fall off if its not tightened correctley, and this applies to the R/H crank too.

Very true. its all about getting the right preload/interference. IMHO adding lube means that the bolt torque goes on creating the interference, not overcoming friction. There is loads of research on fretting, interference and lubrication of bolted connections. good overview available in any good mechanics &materials book. try shigley & mischke mechanical engineering design.

kona

The Idea behind the grease is to fill in the imperfections and make a smoother fit, as a result , reducing fretting? And so give a more "predictable" fit?

From my experience with cars is that grease actually makes the problem of fretting worse.

apoeiguq3094y

kona wrote: »

The Idea behind the grease is to fill in the imperfections and make a smoother fit, as a result , reducing fretting? And so give a more "predictable" fit?

From my experience with cars is that grease actually makes the problem of fretting worse.

Yeah, i think you've hit the nail on the head here with predictable. If the part isn't lubed you never really know how much friction there is going to be pushing the crank along the taper. The grease means that if you apply Xnm of bolt torque - you get an interference of Ymm, consistently.

For other crank types, they rely on splines to transmit the torque, and there's no taper. I don't know if grease helps in that case. I can't see any big disadvantage, and it would surely make it less likely to get stuck on.

TBH fretting is more of an issue with moving parts I'd say, eg an axle passing through a housing. There's (hopefully) no movement between the crank and axle, so fretting shouldn't really ever be a problem. In fact if you have tightened it enough and the interference is good, you shouldn't see any movement between them.

In the car, the grease might not be high quality? or else it might be collecting dirt that acts like a sanding grit to eat away the metal. Same reason why 3in1 is terrible for you chain, collects dirt that erodes the chain.

doozerie

Look, it's quite simple: just lubricate the crank tapers with WD40 and beat the crank on with a lump hammer, locking down with a philips head screw (never mind yer bolts) coated liberally in superglue. Once done, look again at your cranks and if they are Shimano then rip them off and replace with Campag. If the new one is anything other than a double chainset, rip it off again and repeat. And repeat yet again if you've had the nerve to put a standard double on there instead of a compact.

Now, what are you doing with a square taper bottom bracket in the first place? Rip that out, and chuck it and the chainset on the heap with the Shimano and triple and standard chainsets and put on an Ultra-Torque one. Clearly the pedals shouldn't be anything that attaches to your shoes, that's pure lunacy, so transfer the ones from your grandmothers high nellie across to it. You may as well take her bike's mudguards too, and the chain guard to keep your trousers out of the chain.

Then, go for a ride on your newly revamped, and safer, bicycle. You did remember to put on your helmet, of course, to avoid certain death before you leave the garage. Not to mention brightly coloured clothing verging on the visually offensive, etc.

That should wrap up a whole bunch of religious arguments nicely.

kona

apoeiguq3094y wrote: »

Yeah, i think you've hit the nail on the head here with predictable. If the part isn't lubed you never really know how much friction there is going to be pushing the crank along the taper. The grease means that if you apply Xnm of bolt torque - you get an interference of Ymm, consistently.

For other crank types, they rely on splines to transmit the torque, and there's no taper. I don't know if grease helps in that case. I can't see any big disadvantage, and it would surely make it less likely to get stuck on.

TBH fretting is more of an issue with moving parts I'd say, eg an axle passing through a housing. There's (hopefully) no movement between the crank and axle, so fretting shouldn't really ever be a problem. In fact if you have tightened it enough and the interference is good, you shouldn't see any movement between them.

In the car, the grease might not be high quality? or else it might be collecting dirt that acts like a sanding grit to eat away the metal. Same reason why 3in1 is terrible for you chain, collects dirt that erodes the chain.

It was Castrol LM grease, I just have a habit of greasing aything that has metal to metal cotact, as Im sick of undoing seized parts which can be avoided with common sense and lube. The parts had not dirt and in the case of the crank was a polished tail.

I can only see fretting occuring on either low end or worn parts. Parts with a good finish *should* have a predictable fit, if fretting was such a problem the cranks would be matched to the axle.

kona

doozerie wrote: »

Look, it's quite simple: just lubricate the crank tapers with WD40 and beat the crank on with a lump hammer, locking down with a philips head screw (never mind yer bolts) coated liberally in superglue. Once done, look again at your cranks and if they are Shimano then rip them off and replace with Campag. If the new one is anything other than a double chainset, rip it off again and repeat. And repeat yet again if you've had the nerve to put a standard double on there instead of a compact.

Now, what are you doing with a square taper bottom bracket in the first place? Rip that out, and chuck it and the chainset on the heap with the Shimano and triple and standard chainsets and put on an Ultra-Torque one. Clearly the pedals shouldn't be anything that attaches to your shoes, that's pure lunacy, so transfer the ones from your grandmothers high nellie across to it. You may as well take her bike's mudguards too, and the chain guard to keep your trousers out of the chain.

Then, go for a ride on your newly revamped, and safer, bicycle. You did remember to put on your helmet, of course, to avoid certain death before you leave the garage. Not to mention brightly coloured clothing verging on the visually offensive, etc.

That should wrap up a whole bunch of religious arguments nicely.

My face went from :mad: :eek::rolleyes: at WD40 to :P:pac: at Lump hammer haha:pac:

doozerie

I've gotta admit that I've never thought much about the mechanical properties of mating materials when it comes to the topic of greasing square-tapered cranks. I've spent many years not greasing them at all on current and previous bikes and only started greasing them in recent months after I stumbled across a (very heated) discussion about it - well actually the discussion was really about whether square taper cranks are more prone to breaking but the battle was so fierce that many side issues got dragged in and unmercifully bashed about too. There were some very strong arguments on both sides of the greasing debate, by people who clearly deeply understand stuff that I am completely ignorant of. I came away from reading that discussion with a pain in my head but also convinced that greasing the tapers is a good thing to do.

I also came away with a conviction to never invoke the wrath of metallurgical nerds. They just wear you down with facts and the repeated use of words ending in -ium. You'll never look at your bike in the same way again, and your speechium will be permanently impairedium.

kona

doozerie wrote: »

I've gotta admit that I've never thought much about the mechanical properties of mating materials when it comes to the topic of greasing square-tapered cranks. I've spent many years not greasing them at all on current and previous bikes and only started greasing them in recent months after I stumbled across a (very heated) discussion about it - well actually the discussion was really about whether square taper cranks are more prone to breaking but the battle was so fierce that many side issues got dragged in and unmercifully bashed about too. There were some very strong arguments on both sides of the greasing debate, by people who clearly deeply understand stuff that I am completely ignorant of. I came away from reading that discussion with a pain in my head but also convinced that greasing the tapers is a good thing to do.

I also came away with a conviction to never invoke the wrath of metallurgical nerds. They just wear you down with facts and the repeated use of words ending in -ium. You'll never look at your bike in the same way again, and your speechium will be permanently impairedium.

While I can see the Use behind it, I think its given more attention than it deserves. How many times has fretting occured on cranks? How big an issue is it? While greasing is no doubt going to give a better fit, and make it predictable, I dont think its the end of the world if you dont grease the cranks.

In fact Im sure there are many bikes with cranks no greased and never give issue. But as time goes on such arguments are becoming obsolete. External BB FTW! haha

iregk

Right so problem 1 resolved. Took a look at the cranks properly and the large allen key type screw at the crank arm/bottom bracket I could turn off with my finger. Obviously this shouldn't happen so I took it apart, the whole thing and couldn't see anything wrong. Did a regrease and put it back together tightening the screws on the crank arms.

The creaking sound is now gone however another has manifested. When now pressing down on the right crank arm when i get to what would be the 5 o'clock position I hear a crack. Doesn't happen under normal peddling, only when putting some proper torque through it. If I stand up climbing a hill it can get quite loud.

I've checked around the the chain, gears etc.. all is fine there from what I can see. Any clues? Next stop is LBS which will be about a 5 days wait!

Khannie

Interested to hear the replies here. Only this evening my crank started making a funny noise when accelerating or climbing (but not while cruising). This in particular made me very nervous:

seamus wrote: »

As Kona says, if your crank wobbles at all on the axle, then stop riding immediately or you're about five minutes away from needing a new crankset.

seamus

Khannie wrote: »

Interested to hear the replies here. Only this evening my crank started making a funny noise when accelerating or climbing (but not while cruising). This in particular made me very nervous:

I was probably being a bit extreme. But the problem is that if you ride hard on a crank that's loose on the spindle, your will warp the taper and it quickly becomes a write-off. Noise isn't the same. It would be noticeably loose on the axle.

"Five minutes" is an exaggeration, but it's one of those things that you don't take a risk with because there's no way of telling how much damage you're doing. If the crank is loose, stop riding immediately until it's fixed.

Only applies to old-style square tapers btw. The same thing doesn't apply to octalink or hollowtech, though if they feel loose they're probably going to fall off.

iregk

Mine is a tiara set with tiara bottom bracket so I assume that is hallow tech!

Hail 2 Da Thief

iregk wrote: »

Mine is a tiara set with tiara bottom bracket so I assume that is hallow tech!

Did you enter it in a beauty pageant or something? :pac:

seamus

iregk wrote: »

The creaking sound is now gone however another has manifested. When now pressing down on the right crank arm when i get to what would be the 5 o'clock position I hear a crack. Doesn't happen under normal peddling, only when putting some proper torque through it. If I stand up climbing a hill it can get quite loud.

Usually means your bottom bracket is gone or less commonly your pedal bearings are gone. Not that hard to diagnose.
For the pedals, just spin the pedal in your hand, feeling for roughness. The pedal should spin, but not too freely. If it keeps spinning forever after one "flick", the bearings are probably gone. Likewise if it feels rough or needs proper effort to spin, they're gone.
Hollowtechs can really only be diagnosed by removing the chainset and moving the bearing with your finger to feel for roughness. Although if it's really screwed, you'll feel it when spinning the cranks by hand with no chain attached.

I've had success in the past with hollowtech bottom brackets, flushing out the worn side with WD40 or similar, then jamming some more grease on in there. But it's only a stopgap to get rid of the noise, the BB still has to be replaced.

iregk

Hail 2 Da Thief wrote: »

Did you enter it in a beauty pageant or something? :pac:

Dam iPhone auto correct!

Thanks Seamus. The pedals seem fine as in they don't spin and spin and spin and no roughness at all. I'm going to have another crack at it this weekend and see what happens.

Khannie

seamus wrote: »

Usually means your bottom bracket is gone or less commonly your pedal bearings are gone.

Sorry to hijack, but I'm assuming in my case, where the bike only has about 300K on it that the pedals (which are not new) are the likely culprits?

Khannie

Bit of a bump here....I want to cycle in tomorrow but don't want to damage the bike. I can't get the pedals off because I don't have a hex key big enough but it's safe to assume that the bracket on my spanking new bike isn't gone, right? The crank set shows no sign of any movement / all the hex screws are in tight and the pedals are second hand.

kona

Khannie wrote: »

Bit of a bump here....I want to cycle in tomorrow but don't want to damage the bike. I can't get the pedals off because I don't have a hex key big enough but it's safe to assume that the bracket on my spanking new bike isn't gone, right? The crank set shows no sign of any movement / all the hex screws are in tight and the pedals are second hand.

If you cycle, dont be suprised if something goes wrong. Youd be taking a risk. Nobody here can say you will be fine. If your crank is creaking it can be other problems, but the most common is its loose.

Why do you want to remove the pedals, unless you have some exotic pedals, a 15mm spanner will shift them.

Khannie

I have look keo pedals. There's nothing for the spanner to grip. It needs a filthy big hex key which I don't have.

Hmmmm. It's not a creak for me, more a click (I am totally hijacking this thread *cough*). It happens twice on the way down on the left side only and only when I'm accelerating (usually when I'm standing up). If Im cruising, no click.

kona

Khannie wrote: »

I have look keo pedals. There's nothing for the spanner to grip. It needs a filthy big hex key which I don't have.

Hmmmm. It's not a creak for me, more a click (I am totally hijacking this thread *cough*). It happens twice on the way down on the left side only and only when I'm accelerating (usually when I'm standing up). If Im cruising, no click.

In terms of degrees with Crank at the top being zero and then down being 180, where are the creaks? Or do they vary? Maybe the clip mechanism needs to be tightened?

Icyseanfitz

got to love creaks ha my bionicon is still driving me nutty with em, ive replaced all the bearing and bushings in the swingarm/shock pivots as well as having a 2 month old hollowtech slx bb and chainset, even got it all fixed and quite for like a week :rolleyes:, any ideas for a good grease/lube to use on pivots, bb's etc. ? do you even need it with hollowtech?

since i have the new bike i think im about to do a full disassembly of the bionicon just to try and sort my damn creaking out (have no idea where its actually coming from)

Khannie

kona wrote: »

In terms of degrees with Crank at the top being zero and then down being 180, where are the creaks? Or do they vary? Maybe the clip mechanism needs to be tightened?

It was significantly better on the cycle in today (I couldn't resist..what a beautiful day!). Only heard it a few times over the whole 33K commute. I had adjusted my front derailer last night though I was 99% sure that it was nothing to do with that.

Anyway, to answer your question, it happens at say 120 and 150 degrees. Two clicks. Very occasionally 3. I'll check out the clips that's a good idea, though it has happened when I've just been using street shoes on the keo pedals. I'll get a large hex key today though and try the pedal from my crappy BSO to see if it's still there.

Thanks for your help.

Khannie

Well, this came back with a vengeance. In case it happens to someone else / can help the OP: Turns out it was the pedal. I got the appropriate sized hex key (thank you 2 euro store), took the pedal off and took it apart. The bearing looked ok, stuck it back together, greased the threads and put it back in. Presto, no more noise.