Crank Removal

Thanks for the help and the link!

excellent dt, that'd be great. thanks!

someone had to do it!

If you grease your tapers, there is a chance that you may split your crank.

If you grease your tapers, there is a chance that you may split your crank.

Fnaaarrr

everyone seems to have a different opinion on grease. the instructions from my new miche cranks say don't use grease.
but i think it is a good idea to use a little.
@dave: not unless you're superman!

take it slowly getting those cranks off - if you've never used a crank extractor before, it's kindof easy to strip the threads, and Sugino 75's are far too nice to be practicing on...

best thing to do is ensure the threads are clean and get the inner screw / bolt almost all the way out, before you screw the main body on to the crank threads. Get the main body all the way on, as far as it'll go (without using too much torque). Use a good (well fitting spanner), or you may scratch your cranks at this point. Screw the inner bolt back in, ideally using a socket or ring spanner, so that it doesn't slip. You'll meet firm resistance before they give. As soon as you feel this give, stop turning, your cranks should be free from the BB. the crank extractor should come back off by hand.

also, use a good quality tool, some don't have deep / long enough threads. I use BBB, but there are many good ones out there.

I could bring a crank extractor to central beers tonight + spanner, but you can't take it home with you.
PM me before 5:30.

If you grease your tapers, there is a chance that you may split your crank.

yeah but its less then if you dont.

slightly OT, how do you all refit your cranks? hammer and wood, or (just) grease and allen-key/torque-spanner?

i use a hammer, a hack saw and a blow torch

the right way is grease and a torque wrench

everyone seems to have a different opinion on grease. the instructions from my new miche cranks say don't use grease.
but i think it is a good idea to use a little.
@dave: not unless you're superman!

really? I didn't get any paperwork with my Condor-Miche cranks.

I'm of the grease everything school of thought. I don't see how greasing the tapers lightly will cause the cranks to crack. They're more likely to crack if you don't torque them properly.

the bottom bracket and crank are machined to fit each other grease means that the cranks will slide past the stop point causing them to exspand and crack

the bottom bracket and crank are machined to fit each other grease means that the cranks will slide past the stop point causing them to exspand and crack

You'd bust the crank bolt first. You're just not supposed to retighten the bolt after it's properly torqued, because the crank can squirm further up the taper after you've ridden it - if you tighten it then, you can crack it.

I don't grease my tapers!

someone had to do it!

have it done in BLB haha

If you grease your tapers, there is a chance that you may split your crank.

Almost impossible.

Read this: (for those who can't be bothered a summation: grease your spindle flats)

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.

Good advice on Sugino 75 crank / BB maintenance (with pictures !):

[ame="http://www.bikeforums.net/showthread.php?t=208402"]Maintain that sexy (or not so sexy) track BB - Bike Forums[/ame]

slightly OT, how do you all refit your cranks? hammer and wood, or (just) grease and allen-key/torque-spanner?

I would like to see this 'torque spanner' !? :P

Refit your crank arms by greasing the flats of the spindles tapers - pop on the crank arm and then tighten down the crank arm bolts - preferably with a torque wrench to somewhere around 35-40 Nm (check the crank manufacturers website for a more precise torque setting).

Don't forget to use a washer on your crank arm bolts and grease the threads and underside of the bolt head.

kewl thanks tynan. I've never used a torque wrench*, I grew up fitting cottered cranks (well, actually breaking cotter-pins), so my wrench/spanner arm is now pretty good at getting the right torque. I wasn't sure whether a mallet was required to pre-seat the crank before tightening the crank arm bolts.

• though I do own a torque spanner :-)
  

I have a little dial installed in my right arm, it tells me how much torque i'm applying to anything.

By the way, ricky gervaise is on TV on GTA IV!! Ha

Quick question... I'm removing stock specialized cranks form an old langster but the buggers won't come off (yes i am using a crank puller). How much force should i put in, but wary of ruining the threads. Any help much appreciated!

Jim

just make sure that the crank puller is fully in the cranks first, then try again, it takes quite a lot of force

Have you removed the bolt/nut which holds the cranks to the bottom bracket axle? If the answer is yes, flickwg's advice is sound. Make sure the crank puller is threaded on absolutely as far as it will go, then step up and be prepared to give it a bit of wellie. It sometimes helps if a friend holds the bike for you.

Got the fucker, just needed a bit of elbow grease, cheers guys.