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Ceramic Bearings http://weightweenies.starbike.com/forum/viewtopic.php?f=3&t=595 
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Author:  spytech [ Tue Nov 04, 2003 9:11 pm ] 
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nikh wrote: You got me thinking about replacing the bearings in my King headset
i think in the future, all bearings will be ceramic, from what i read its easier to make a more perfectly rounder ball bearing. quality is almost always great. so, everyone lets upgrade to a smoother rolling lighter future 
Author:  Weenie [ Tue Nov 04, 2003 9:11 pm ] 
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Author:  Joel [ Tue Nov 04, 2003 9:39 pm ] 
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The WR bike has just the lightest components, not the best 
Author:  nicrump [ Tue Nov 04, 2003 9:43 pm ] 
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ok,ok. i said a while back. it was '93 to be exact. came back from interbike with them. so, that said, they have come a long way. 
Author:  nicrump [ Tue Nov 04, 2003 9:49 pm ] 
Post subject:  more than a weight benefit, for speed weenies as well 
The centrifugal load is described by F= mT2R where m is the weight of the ball. Because the density of silicium nitride is 60% of steel, the centrifugal load is reduced by using these balls with 60%. As a consequence the running speed can be increased up to 30%. Because the Emodulus of silicium nitride is about 1.5 times that from steel, a smaller contact surface exists with the consequence of a high contact pressure. So, the benefit of a small centrifugal load is limited by the large Emodulus. From Hertz theory it follows that the maximum load for the combination steel silicium nitride reduced with 30%. A decrease of 60% centrifugal loading in combination with a 30% decrease in load capacity finally results in an increase of running speed with only 15%. A third effect, that frictional heating between the ceramic balls and the steel rings is less, further positively affect the maximum running speed. 
Author:  nikh [ Tue Nov 04, 2003 10:41 pm ] 
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Thanks for that....I think 
Author:  spytech [ Tue Nov 04, 2003 10:59 pm ] 
Post subject:  Re: more than a weight benefit, for speed weenies as well 
nicrump wrote: The centrifugal load is described by F= mT2R where m is the weight of the ball. Because the density of silicium nitride is 60% of steel, the centrifugal load is reduced by using these balls with 60%. As a consequence the running speed can be increased up to 30%.
Because the Emodulus of silicium nitride is about 1.5 times that from steel, a smaller contact surface exists with the consequence of a high contact pressure. So, the benefit of a small centrifugal load is limited by the large Emodulus. From Hertz theory it follows that the maximum load for the combination steel silicium nitride reduced with 30%. A decrease of 60% centrifugal loading in combination with a 30% decrease in load capacity finally results in an increase of running speed with only 15%. A third effect, that frictional heating between the ceramic balls and the steel rings is less, further positively affect the maximum running speed. did you think that out yourself, or do you have a source? 
Author:  JTC [ Wed Nov 05, 2003 3:55 am ] 
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This all sounds very interesting. Will it be possible to replace the bearing in the head set and hubs? We need a guinea pig to try this out. Any ideas on real weight savings? Is it going to be worth the cost and effort? 
Author:  Superlite [ Wed Nov 05, 2003 5:51 am ] 
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In the words of Master P. NAH!! I called one of those places today, to replace the bearings in my rear hub around $700!!!!!!! HOLY SNIHCKIES!! 
Author:  nikh [ Wed Nov 05, 2003 1:04 pm ] 
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Superlite wrote: In the words of Master P. NAH!! I called one of those places today, to replace the bearings in my rear hub around $700!!!!!!! HOLY SNIHCKIES!!
Dadadamnnnnnnnnn, thats a whole lot of money!! 
Author:  Superlite [ Wed Nov 05, 2003 5:23 pm ] 
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TELL ME ABOUT IT!! i could buy another set of my wheels for that much. Guess thats why Z 3 wheels cost 3 g's, vs, 1350 for an almost identical set of 303's. I don't know about you guys but unless I start ridding in the Tour regular bearings are plenty good for me. 
Author:  nikh [ Wed Nov 05, 2003 5:35 pm ] 
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I'd like some FIR wheels for my MTB 1200g!! But they cost around 2.5K!! 
Author:  Superlite [ Wed Nov 05, 2003 5:38 pm ] 
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Do those have ceramic bearings? Or just a random thought? 
Author:  nikh [ Wed Nov 05, 2003 5:39 pm ] 
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Just dreaming along with ceramic bearings!! 
Author:  Kirkster [ Wed Nov 05, 2003 5:44 pm ] 
Post subject:  Re: more than a weight benefit, for speed weenies as well 
spytech wrote: nicrump wrote: The centrifugal load is described by F= mT2R where m is the weight of the ball. Because the density of silicium nitride is 60% of steel, the centrifugal load is reduced by using these balls with 60%. As a consequence the running speed can be increased up to 30%. Because the Emodulus of silicium nitride is about 1.5 times that from steel, a smaller contact surface exists with the consequence of a high contact pressure. So, the benefit of a small centrifugal load is limited by the large Emodulus. From Hertz theory it follows that the maximum load for the combination steel silicium nitride reduced with 30%. A decrease of 60% centrifugal loading in combination with a 30% decrease in load capacity finally results in an increase of running speed with only 15%. A third effect, that frictional heating between the ceramic balls and the steel rings is less, further positively affect the maximum running speed. C'mon Guys just ride the damn Bike! 
Author:  nicrump [ Wed Nov 05, 2003 6:07 pm ] 
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a valid point, but the wrong forum. this is about geeking out over weight and physics. 
Author:  Weenie [ Wed Nov 05, 2003 6:07 pm ] 
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