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PostPosted: Tue Mar 12, 2013 2:45 pm 
retrobike rider
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is a quill stem an interference fit?
does a quill stem need greasing or copper slipping before fitment?


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PostPosted: Tue Mar 12, 2013 3:36 pm 
Gold Trader / MacRetro rider
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twain wrote:
is a quill stem an interference fit?
does a quill stem need greasing or copper slipping before fitment?



I think you know my answer :wink: :lol:


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PostPosted: Tue Mar 12, 2013 4:42 pm 
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Charlieboy28 wrote:
Taper Shaft or Bushing

A common method of introducing an interference is to manufacture a tapered shaft and tapered bore. At installation, axial force is applied (by tightening a nut against a thread on the taper shaft's end) to advance the hub along the tapered shaft
Furthermore, you'll need a method for removing the part later.

sounds like a a square taper crank to me and it is an interference fit as it achieves the interference fit by the crank arm being driven up the tapered shaft and there is some degree of deformation of the aluminium: xmas-big-grin: :xmas-big-grin: :xmas-big-grin:

and i'm not an engineer im just always right :P :P

and i dont care what the non grease gestapo have to say


The word ‘interference’ in your sentence, presumably quoted from another source, does not refer to the type of fit but simply says an interference is created between the two surfaces – which is actually obvious. This is an important distinction. Any two surfaces when secured together, especially with load (a force of some kind like bolt, clamp, pressure etc), will create interference between those surfaces but this in itself does not make it an interference fit. The term “interference fit” means that the security of the fixture is achieved by the interference between the two components. If this were true for bicycle cranks then everybody could permanently remove their crank bolts in full confidence that their cranks would not fall off while riding. Of course we know this to be not the case and the reason why not is because a bicycle crank taper assembly is not an interference fit, it is a clearance fit secured fast by a bolt (or sometimes a nut). Weight weenies worldwide would rejoice if crank tapers were interference fits because they could all save a few grams and almost certainly would’ve been doing so already since decades. This is a nice discussion but please let's not fly in the face of facts. This is engineering fact not just an opinion and if anyone insists on continually disagreeing with fact then OK go ahead.. :roll:


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PostPosted: Tue Mar 12, 2013 5:11 pm 
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RadNomad for president! I like his style 8)

Admittedly though, does the pigeon holing of a square taper fixture really help the grease or not question? I for one have difficulty seeing it does.


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PostPosted: Tue Mar 12, 2013 5:17 pm 
retrobike rider / Gold Trader
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Can we compromise and say its a semi interference fit. As cranks don't come off when you undo the bolt. We also swap out the steel bolts to an ally bolts. If it really is a matter of how far the crank slips down the taper. Are we not saying the same thing. More grease less torque. No grease more torque to achieve the same result.


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PostPosted: Tue Mar 12, 2013 5:19 pm 
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John wrote:
Think a point has been missed here. Let's cool our heels please chaps.


Sorry...

...touchy subject for me :|


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PostPosted: Tue Mar 12, 2013 5:37 pm 
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Actually a greased fastener requires more torque to retain the same as an un greased fastener


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PostPosted: Tue Mar 12, 2013 5:58 pm 
retrobike rider / Gold Trader
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See now im completely befuddled , is the whole point not to have the crank on the shaft at the correct or optimum point, i.e not too far so that it damages or deforms the taper?? if we grease, surely it reduces friction and the crank slides on easier, less force or torque is required to get it to that optimal place on the shaft . if regardless of grease or no grease we get it to that point and it is then held in position purely by the bolt as it is not an interference fit, then greasing becomes irrelevant and these 17 pages have been completely pointless. :?

or am i missing something as usual


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PostPosted: Tue Mar 12, 2013 6:00 pm 
retrobike rider / Gold Trader
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and just to add the other guy i quoted said the point of greasing is to reduce friction and so reduce the little tiny bits of metal that shave off that causes creaking cranks.


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PostPosted: Tue Mar 12, 2013 6:57 pm 
retrobike rider
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A crank is only on too far if it bottoms out either against the bolt or against the shoulder, for want of a better word, where the taper stops being square. The tollerances from crank to crank and taper to taper means that anywhere in-between is fine.

grease if the manufacturer says so, don't grease if they say don't. If it is a mixmatch then go for the crank manufacturer. If it says nowt then just stick the crank on as it is or whatever is on your fingers as they don't know themselves and have no advice.


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