Why Ceramic Bearings??? (1)

[Ivanb]

The friction in bearings depends on; seals, shields, cage, lubrication, clearance and type of balls (steel vs. ceramic). <?:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

To demonstrate this I upgraded a Shimano Dura Ace hub so standard ball bearings could be fitted into the hub. A 12g steel ball was attached to the carbon rim and the wheel placed in a front fork. By releasing the wheel from the same point each time and by counting the motions until it stops, difference in bearing friction could be detected

RS1  Means Rubber Seal (contact)

Z       Means Shield (non contact)

RZ    Means Rubberised Shield (light contact)

 

6000 2RS1 steel bearing, grease                           3

6000 RS1 steel bearings, grease                           6

6000 RS1 steel bearings, oil                   9

 

6000 Z steel bearings, grease                                            21

6000 Z steel bearings, oil                                    52

 

6000 RZ hybrid bearings, oil                             118

         Used in 2001 Tour de France

          3-4000 km without lubrication. 

6000 RZ hybrid bearings, oil                             325

 

Number of motions until the wheel stops.

(The higher the number, the lower the friction)

This is the number of revolutions so yesthey do make diffrence

[Ivanb]

Let me throw a spanner in the works.

 

Our new SABB Self aligning Bottom bracket does fantastic things.

 

It allows the bearing to stay paralell to the axle. mmm think about it each time you put pressure on one crank the axle bends and the top and bottom of the bearings on each side stay in contact. With the SABB it stays aligned

 

http://www.rotorbike.com/2006/sabb.htm

 

 

[Gumpole]

I had a look at the website, very interesting that Rasmussen endorses there product.

Rasmussen is a brilliant cyclist (in the yellow jersey too)... but apparently weights his cycling jerseys!

 

I think that this attitude sums up the whole ceramic bearing debate!

[AttieSlabbert]

Ivan,

Only give the following info on your ceramic bearings please!

density, Vickers hardness, compressive strength and composition.

Thanks a lot!

[SwissVan]

Dear Attie

 

Ceramic bearings aren't all they're cut out to be.

 

Yes they're harder' date=' but now they're destroying their softer (steel) races very quickly. Hubs are more expensive to replace than bearing balls.

 

Yes they're lighter than steel but the saving on 38 balls is less than the weight of a strand of spaghetti. Let's get realistic.

 

Bicycle wheels spin relatively slowly compared to hard disks and turbo chargers, where ceramic works nicely. There is no heat build-up in bicycle wheels.

 

 

Ridgidity - just hardness in this case, see point one.

 

Anti-magnetic? Who cares. Good mechanics keep their balls togher with a magnet and retrieve stray bearings with magnets. Imagine loosing a R20 bearing ball and a magnet can't find it!

 

Everything is prone to contamination. Dirt doesn't care what the ball is made of.

 

Galvanic current. C'mon... lets get real.

 

The rest of the "benefits" is just hardness and polish repackaged.

 

50% reduction in rolling resistance? Not so, most of a wheel's rolling resistance comes from the tyre. The bearing's rolling resistance is so small, that a 50% reduction is meaningless and cannot be measured over any reasonanble race. I don't for a minute believe these benefits cited here.

 

A bike is not a turbocharger. Steel is just fine.

 

JB

 

[/quote']

 

JB - Pretty well summed up

 

You kind of left out 2 points - Sales marketing and turnover