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PostPosted: Tue Feb 26, 2013 10:40 pm 
Retro Guru

Joined: Tue Feb 06, 2007 5:50 pm
Posts: 946
Location: Over there -->
retrobate wrote:
From the Raceface data.

Cranks tend to "suckon" to a greased spindle approximately 0.5mm
(0.020") further than they would onto a dry spindle
using the same torque value (28 ft/lbs. max.) on the
crank bolt. We have taken this into cons ideration in
the CNC machining of our tapers to ensure it is not a
problem.

Presumably their CNC machine was lubricated with finest extra virgin viper oil? :twisted:


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PostPosted: Tue Feb 26, 2013 11:13 pm 
Old School Grand Master
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Joined: Wed Apr 12, 2006 12:33 pm
Posts: 11105
Location: The Home Of Mountain Biking, And All Great Things.
Of course tightening the same amount will require less torque with lube.

It does not automatically follow that tightening to the same rating as recommended for a dry fit will cause deformation.

I have never used a torque wrench to tighten cranks on my own bikes, though I have to add my experience mostly pre-dates the newer materials.


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PostPosted: Tue Feb 26, 2013 11:14 pm 
Old School Grand Master
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Location: Heathfield, East Sussex
Perhaps the Raleigh Grifter was named with a healthy dose of tongue in cheek afterall... :lol:


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PostPosted: Tue Feb 26, 2013 11:22 pm 
Gold Trader / MacRetro rider
Gold Trader / MacRetro rider

Joined: Thu May 06, 2010 10:05 pm
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Location: Aberdeen
No More Nails... works like a charm :twisted:

I used to grease, then I read (on the interweb :shock: ) that it might allow the crank to slide further up the tapers & cause damage, so now I don't grease, and I've never had any issues with either method in over 20years of MTB.
Hell, in ye olden days I used to whack the cranks onto the greased axle with a lump hammer and a block of wood before tightening the bolts down, and those cranks never worked loose :lol:


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PostPosted: Tue Feb 26, 2013 11:51 pm 
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Location: The Cock Inn, Tillett, Herts
I don't grease, for boring engineering reasons.


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PostPosted: Wed Feb 27, 2013 8:35 am 
Retro Guru
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Joined: Sun Dec 18, 2005 10:44 am
Posts: 461
Location: Vancouver
Haven't we all realized that it really doesn't matter yet? I've been installing bottom brackets both privately and professionally for the last 24 years and haven't had an issue with either technique.


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PostPosted: Wed Feb 27, 2013 10:24 am 
retrobike rider
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C'mon - let's see if we can get this thread to 10 pages of going round in circles.


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PostPosted: Wed Feb 27, 2013 10:53 am 
.o.T.M Triple Crown Winner
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gerryattrick wrote:
WOW! Six pages of views and no significant majority on either side. That must show it doesn't matter either way so stick with whatever method you prefer, it won't make a bit of difference apparently.


It's only my opinion. Perhaps it's idiot but since I've got titanium parts, I grease quite everything with cupper grease.


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PostPosted: Wed Feb 27, 2013 11:05 am 
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24pouces wrote:
gerryattrick wrote:
WOW! Six pages of views and no significant majority on either side. That must show it doesn't matter either way so stick with whatever method you prefer, it won't make a bit of difference apparently.


It's only my opinion. Perhaps it's idiot but since I've got titanium parts, I grease quite everything with cupper grease.


Sound reasoning, because if you don't they may never come apart...

,,,had to cut a lightweight 'quick release' skewer off my Explosif because the alloy nut had 'cold-welded' to the titanium thread! :facepalm:


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PostPosted: Wed Feb 27, 2013 11:53 am 
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Joined: Thu May 08, 2008 4:18 pm
Posts: 2336
I used to think I didn't grease, then realised I'd been wiping the spindles with a greasy rag before fitting the cranks, so actually I'd been greasing all along. Whatever you put in there won't still be there by the time the crank's tight anyway, it all gets squooged out (you can see metal-to-metal contact on the spindle when you take the crank off).

I don't believe* it's possible to damage the tapers of a crank by overtightening, assuming a normal human and a spanner of conventional length. If they go on too far, they were already broken. The thing that knackers crank tapers is undertightening or just fatigue.

*this is exactly that, a belief, no sums involved, merely some experimentation ;)


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