greasing the tapers

jonnywilkinson · May 2007

just can't fathom what is causing a nasty creaking sound from the cranks when i am out of the saddle. i have worked out its not the pedals, or chainring bolts - so am starting to think it's the bottom bracket.

before i get LBS to take a look at it was just wondering whether it would be worth greasing the square tapers? i thought you weren't meant to but will give anything a shot. it's a mirage bottom bracket and athena chainset.

all advice welcome, as ever.

Jonny
FGG #2545 & #2983

Unknown · May 2007

Received wisdom says "no grease". Personally I always smear with copper grease (or any to hand if necessary). Like to think that someone somewhere in 25 years time will say a silent thank you when they are trying to remove the cranks.

Can also prevent creaking!

d.j.
"Like a true nature's child,
We were born,
Born to drink mild"

jonnywilkinson · May 2007

cheers davej, my feeling is that is can't do any harm and I bow to superior experience,

all the best,

Jonny
FGG #2545 & #2983

Mickle · June 2007

NEVER grease the crank tapers!

(twenty years in cycle shops, one time cycle team mechanic and currently responsible for the maintenance and upkeep of three hundred bikes)

Mick Allan, Operations Manager, Company of Cyclists.

Dumbo.

Unknown · June 2007

If the creak only happens when you are out of the saddle I would first look at the headset, bars and stem.

Nobody ever got laid because they were using Shimano

piedwagtail91 · June 2007

if you're using look pedals and cleats it could be them.

msb123 · June 2007

why is received wisdom 'no grease'? - i always grease them to stop them binding and make them easier to get off

Unknown · June 2007

"why is received wisdom 'no grease'?"

I believe that the thinking is that grease will allow one to pull 'em up tighter than otherwise the case, leading to distortion and possibly cracking the crank arm around the mounting hole.

Yer teks yer choice, IMHO.

d.j.
"Like a true nature's child,
We were born,
Born to drink mild"

msb123 · June 2007

so with a bit of common sense while wielding the spanner you can have the best of all worlds - cranks that aren't overtight and can be easily removed!

wotbus@ · June 2007

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by davej

"why is received wisdom 'no grease'?"

I believe that the thinking is that grease will allow one to pull 'em up tighter than otherwise the case, leading to distortion and possibly cracking the crank arm around the mounting hole.

Yer teks yer choice, IMHO.

d.j.
"Like a true nature's child,
We were born,
Born to drink mild"
<hr height="1" noshade id="quote"></blockquote id="quote">

Torque settings remain unchanged - no electrolytic action between steel and alloy - easier to get on/off - may even stop the creaking so try it.
(forum followers can be forgiven I am a secret lube rep conjuring up trade for chain lube/seatpost grease etc - Honest - I'm not [:D])

Arellcat · June 2007

Having also done time in a well known bike shop's workshop, once upon a time, we always greased crank tapers. Like davej, I tend to use copper grease.

For what it's worth, Jobst Brandt's erudite treatise on crank tapers and crank failure suggests that grease should be used. To which I might add, I split a LH crank which was admittedly rather old and used, by retightening several times.

--
Windcheetah 202
2001 Speedmachine

Asterixcp · June 2007

..from previous experience on the forum, this question is in the same league as asking which is the correct end to open you boiled egg.

FWIW, I am a non-greasing, broad-ender[;)]

Pour vivre heureux, vivons le v‚lo..

Fab Foodie · June 2007

Been greasing mine (and the bikes) for at least 25 years with no ill effect. Just like wotbus said...

The pessimists of this world are rarely disappointed....
Fab's TCR1

hubgearfreak · June 2007

i'm a greaser[:D]

wotbus, you've no need to apologise for you lube peddling antics.

my bicycle runs like a well oiled machine...actually it is one

in all metal to metal assembly, grease is good[:)]
although i'm sure there are exceptions, i can't think of one

The Raucous AUK · June 2007

A few weeks back I had an annoying creak from the chainset area and greased the BB axle tapers which cured the problem. As long as the crank bolt (or the corresponding thread in the axle) isn't greased then I can't see the problem.

jpembrokecp · June 2007

Hi, my name's Jamie, and I'm a crank greaser.

well, yes and no......but mainly no.

maddog_2cp · June 2007

no grease

as all the manufacturers recommend.

Drop bars are a historical accident...... discuss

Ken Night · June 2007

A creaking as you're out of the saddle can be the things mentioned above and also the BB cups. A click can often be the pedals

FWIW, I'm a greaser (copperslip) and a little ender (the arguments are too well known to rehearse them here-non greasers and big enders are just folk trying to be controversial against pure logic and reason

"I once prayed to God for a bike, but quickly found out he didnt work that way...so I stole a bike and prayed for his forgiveness"

Asterixcp · June 2007

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Ken Night

non greasers and big enders are just folk trying to be controversial against pure logic and reason

<hr height="1" noshade id="quote"></blockquote id="quote">

Not at all. Being a Scot, I can't see the point of wasting grease where it's not needed, although I am not so mean as to open the small end of the egg just to make it last longer[;)]

Pour vivre heureux, vivons le v‚lo..

Tom Butcher · June 2007

No grease and little ender.

I had a similar creak and one pedal had developed a bit of play in the bearings.

Warning about well known bike shop removed at request of moderators.

Dickie · June 2007

The fit of a taper relies on metal to metal contact, so no grease.

maddog_2cp · June 2007

I suspect the reason cranks creak isn't because the owners/builders failed to use grease but that they didn't fit them properly in the first place.

45Nm is recommended and is a fair amount. Fit dry to clean tapers and it won't budge or creak, I promise.

Drop bars are a historical accident...... discuss

Steve928 · June 2007

I grease Mirage SC and Centaur AC BB tapers as IME it's the only way to stop the cranks 'ticking'.
But I don't grease new Centaur BB (the œ30 one) tapers as they're fine without: there's much more flat and less rounded shoulder on these tapers to support the crank.

Oh and I use blue Loctite on my titanium BB tapers, as otherwise they creak with or without grease. That was recommended by Raceface for titanium BBs and seems to work great.

Unknown · June 2007

9 greasers, 6 non so far!

Purely a matter of choice I conclude!

d.j.
"Like a true nature's child,
We were born,
Born to drink mild"

piedwagtail91 · June 2007

i don't grease the tapers, just the bolts, then use a torque wrench to tighten them. haven't had any problems yet. ( 9-7!!)

Dickie · June 2007

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by maddog 2

I suspect the reason cranks creak isn't because the owners/builders failed to use grease but that they didn't fit them properly in the first place.

45Nm is recommended and is a fair amount. Fit dry to clean tapers and it won't budge or creak, I promise.
<hr height="1" noshade id="quote"></blockquote id="quote">

Spot on, the crank and spindle should be clean and dry. The crank should not bed on grease film, even if it is only microns thick.
Every second hand bike I have bought has had loose cranks.

pbiggs · June 2007

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Dickie

The fit of a taper relies on metal to metal contact, so no grease.<hr height="1" noshade id="quote"></blockquote id="quote">The combination of pressure from the expanded crank* and the bolt keeps it on. When fitted with a good amount of torque, it takes a hell of a lot more than a bit of grease to make the cranks come off. Then it's just not a concern at all in reality.

I'm convinced that the vast majority of problems with square taper cranks are caused by them being fitted not tightly enough in the first place. Grease is not essential, but cranks are more likely to be fitted tightly if grease is used, especially by those not using a torque wrench.

Personally I've had fewer problems, in fact no problems whatsoever with cranks, since I started fitting with grease a few years ago. Potential problems with my cranks are very very low on my list of worries.

* The aluminium crank is elastic enough for the hole to become larger as it's fitted on the steel spindle. It then conforms exactly to the shape of the spindle and ensures a close fit. Grease is squeezed out during fitting. Any smear of grease left will be no problem. The crank isn't relying a small amount of friction. The amount of forces involved are massive and grease to them is nothing.

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Every second hand bike I have bought has had loose cranks.<hr height="1" noshade id="quote"></blockquote id="quote">Because they were not fitted tightly enough to begin with. They probably were not fitted with grease.

~Pete

pbiggs · June 2007

I bet everyone hasn't clicked the link mentioned ealier, so here is the whole article by Jobst Brandt:

Subject: 8f.11 Installing Cranks
From: Jobst Brandt <jobst.brandt@stanfordalumni.org>
Date: Tue, 2 May 2006 10:25:45 -0700

> My cranks get loose, quite quickly too; over about 10 miles or so
> from being solid to flopping about in the breeze. Any suggestions?

One or both of the cranks are ruined! Once ridden in the "floppy"
mode, the tapered square bore of the crank has been deformed and can
no longer be secured on a spindle. Install and properly tighten new
cranks on the spindle after lubricating the facets. Proper tightness
should be achieved with a torque wrench or by a skilled hand.

The admonition to not lubricate the facets of the spindle finds life
mainly on bicycles. Having discussed the "dry assembly" rule with
crank manufacturers, I discovered that they had warranty claims from
customers who split cranks. However, that cranks cannot be split by
over-tightening can be shown by attempting to do so. An M8x1 screw is
not strong enough to split a major brand crank.

Failure from "over-tightening" is caused by repeated re-tightening of
properly installed cranks. In use, an aluminum crank squirms on its
taper and, because the retaining bolt prevents it from moving off the
taper, it elbows itself away from the bolt and up the taper ever so
slightly. The resulting loss of preload, after hard riding, can be
detected by how easily the bolt can be turned.

Loss of crank bolt preload is greater on left than the right cranks,
because left cranks transmit torque and bending simultaneously while
right cranks transmit these forces separately. The left crank
transmits driving torque through the spindle to the right crank and
chainwheel while the right crank drives the chainwheel directly.
Besides that, the right crank transmits torque to the spindle only
when standing on both pedals. With the right foot forward (goofy
footed) this causes the only reverse torque on the spindle.

Mechanics, unaware of why crank bolts lose preload (and commensurate
crank tightening), have re-tightened bolts until cranks split. No
warnings against re-tightening properly installed cranks are evident
although it is here where the warning should be directed rather than
at lubrication.

Because friction plays no role in torque transmission, preload in the
press fit must be great enough to prevent elastic separation between
the crank and spindle under torque and bending. This means that no
gap should open between crank and spindle facets under forceful
pedaling. Crank bore failure occurs when the press fit is loose
enough that a gap opens between spindle and crank. Torque is
transmitted by both leading and trailing half of each facet, contact
pressure increasing and decreasing respectively. In the event of
lift-off, the entire force bears only on the leading edge of facets
and causes plastic deformation, causing the bore takes on a "pin
cushion" shape (loose crank syndrome). Subsequent tightening of the
retaining screw cannot correct this because neither the retaining bolt
nor crank are strong enough to re-establish the square bore.

The claim that a greased spindle will enlarge the bore of a crank and
ultimately reduce chainwheel clearance is also specious, because the
crank cannot operate in a plastic stress level that would soon split
the crank in use. However, increased engagement depth (hole
enlargement) may occur without lubricant, because installation
friction could ream the hole.

With or without lubricant, in use, cranks will make metal-to-metal
contact with the spindle, causing fretting erosion of the steel
spindle for all but the lightest riders. Lubricating the spindle for
assembly assures a predictable press fit for a given torque. Without
lubrication the press is unknown and galling (aluminum transfer to the
steel spindle) may occur during assembly. After substantial use,
spindle facets may show rouge and erosion from aluminum oxide from the
crank, showing that lubricant was displaced.

Crank "dust caps" have the additional duty to retain loose crank
bolts. Because crank bolts lose preload in use, they can become loose
enough to subsequently unscrew and fall out if there is no cap. If
this occurs, loss of the screw will not be noticed until the crank
comes off, after the screw is gone.

dave5ncp · June 2007

From persi=onal experience, albeit a long time ago, I'd suggest you'd notice a loose square-taper crank well before it fell off.

 please pretend there's a horizontal line here. I couldnt work out how to put one in.
You stir my natural emotions

Asterixcp · June 2007

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by pbiggs

I bet everyone hasn't clicked the link mentioned ealier, so here is the whole article by Jobst Brandt:

Subject: 8f.11 Installing Cranks
From: Jobst Brandt <jobst.brandt@stanfordalumni.org>
Date: Tue, 2 May 2006 10:25:45 -0700

> My cranks get loose, quite quickly too; over about 10 miles or so
> from being solid to flopping about in the breeze. Any suggestions?

One or both of the cranks are ruined! Once ridden in the "floppy"
mode, the tapered square bore of the crank has been deformed and can
no longer be secured on a spindle. Install and properly tighten new
cranks on the spindle after lubricating the facets. Proper tightness
should be achieved with a torque wrench or by a skilled hand.

The admonition to not lubricate the facets of the spindle finds life
mainly on bicycles. Having discussed the "dry assembly" rule with
crank manufacturers, I discovered that they had warranty claims from
customers who split cranks...
<hr height="1" noshade id="quote"></blockquote id="quote">

No, not convinced. Why didn't they have warranty claims from customers who didn't grease the cranks, eh? And why didn't he ask them why cranks should not be greased?

But anyway, I don't have any trouble with ungreased cranks. I'm a heavy rider who tours in the hills, I give my cranks a hard time. Why I should I start greasing them? Will it make them turn faster? Will it make them lighter?[;)]

Pour vivre heureux, vivons le v‚lo..

Spinacilight · June 2007

Grease and small end.

greasing the tapers

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