The correct way to install cranks

So the cranks on the mercian are creaking on hill climbs which I don't like

So what do I do

I am tempted to squirt a little WD40 in there

Leave it overnight

And then tighten up

I thought I might ask if there was a 'correct' way

Not ever having the opportunity to go to bike mechanic university

check:

pedals
chainring bolts
crank bolts

make sure all is tight, and check for any play.
if it still creaks then attend to the BB

Roger Wilco Squadron Leader ...:)

Do what RPM said, but before taking the BB out try this...

Do you have a crank puller? try taking off the cranks and cleaning the taper of the BB and the inside of the square taper of the cranks, then do them back up nice and tight.
Sometimes it's just a bit of grease/grit which causes the noise. I had exactly the same trouble and just did that to mine last night and it sorted it.

Unless there is a lot of play in the BB or it's crunchy/sticky when you turn it then it's probably fine.

It's probably your knees...

Strip it, clean it, grease it and re-fit it. It's the only way to be sure.

Clean and grease the axle, check for play in the BB, check pedal bearings, tighten up saddle bolt... and then discover that the source of the creaking is a crack in your seat tube, as has just happened to me. Poo.

Oh so you are supposed to GREASE the axles maybe that's it..;)

grrrrrr!!

Hey quick tip,

Never, never, ever use WD40 for lubing your parts. WD40 strips away grease leaving your parts bare metal. Metal on metal causes a lot of friction and will wear away your parts. Only use WD40 if you plan on eventually wiping it off and re greasing with copious amounts of grease.

Hey quick tip,

Never, never, ever use WD40 for lubing your parts. WD40 strips away grease leaving your parts bare metal. Metal on metal causes a lot of friction and will wear away your parts. Only use WD40 if you plan on eventually wiping it off and re greasing with copious amounts of grease.

+1

Chain ring bolts were loose and all

Next question is can you overtorque your cranks when fitting them up after a liberal application of GREASE

yeah, you split the cranks ;) :o

Time for that post again . . . (summation = grease them tapers)

Q: 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 greasing the tapered square ends of the spindle. Proper tightness should be achieved with a torque wrench or by a skilled hand.
The admonition not to grease the spindle finds life mainly in the bicycle trade. When I discussed the "dry assembly" rule with crank manufacturers, I discovered that they had warranty claims from customers who split cranks. However, cranks cannot be split by overtightening them. This can be proven by attemting to do so. An M8x1 bolt 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. Doing this with the right foot forward (goofy footed) is the only time the spindle transmits reverse torque.

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.

Jobst Brandt

Oh dear two lines in and no torque wrench what is a eastern chubby grinner to do ? Imust admit I always thought cranks went on dry

they go on dry. the post above is from an oppressed german engineer ;)

So they went on about 80% of maximum strength on a 12inch bar

With grease

And if they fall off I am blaming Tynan for putting new fangled johnny foreigner ideas in my head

yes.

jobst brandt article, fantastic.

Cleared up a lot of mixed up ideas I had in my noggin.

grease or no grease on axle tapers is this forum's equivalent to the problem of evil it seems...

the german was right

100 miles and several steep hills

not a sound ...:)

the german was right

100 miles and several steep hills

not a sound ...:)

:)