SRAM Ceramic BB

[jharsha]

Anybody upgrade their Force BB to the Red Ceramic one? If so was there a noticeable difference in the ease of pedaling? Thanks.

Jim

[Grant McLean]

Didn't you hear?

You don't even have to pedal the ceramic one!

;)


-g

[SoCalSteve]

Didn't you hear?

You don't even have to pedal the ceramic one!
;)


-g

Now thats my kind of bottom bracket!!!

Just sayin'

Steve

[spiderman]

and my ottrott had the ceramic sram bb installed
with the cranks
and they were so sweet and smooth
and spinning freely on the workstand...
then i noticed the bike shop owner
with his ipod/remote control...

[Tobias]

Anybody upgrade their Force BB to the Red Ceramic one? If so was there a noticeable difference in the ease of pedaling? Thanks.

JimJim, I think what some of these smarta$$ comments are saying is that it's not possible for there to be a "noticeable difference" in pedaling effort.

Bearings are already well above 99 percent efficient, so even if ceramic bearings had "zero" friction, there is no way a rider would be able to feel that pedaling was easier.

[swoop]

i have one with ceramic bb's and one without... its subtle. one is not better.. just different... but only if you really try and notice.
the only place i'd really put them is in the wheels.

[Dave B]

Well, this may nto help you roadies, but I put one on my mountain bike and the difference in the stand was pretty remarkable. I have never seen a mtb crank spin as freely as it did when i made the switch.

This is also between a shimano XTR BB and the SRAM one. Now when I am riding it, I am sure it is just in my head. The BB may be making less drag, but I think it is such a small difference in mtbing that if I think it is a benefit that the marketing hype did its job.

[jbrainin]

My understanding of ceramic bearings is that they were designed for use in circumstances where they would experience 10000 rpm or more. If true, there is nothing on a bicycle that would benefit from the use of such bearings. Certainly not a bottom bracket that spins maybe 150 rpm and not even for wheels where hub bearings experience about 300 rpm when rolling at 25 mph.

I suspect one could here the difference between cryogenically frozen audio cables and non-frozen cables sooner than one would detect any difference between steel and ceramic bearings in a bottom bracket or a hub.

Jonathan

[Tobias]

Below you can see that ceramic bearings can be more efficient – based on one bearing supplier.

If one spins the BBKT by itself, the rate of coastdown could be significant since friction may be reduced by as much as half (i.e. -- 0.42 versus 0.17) or more. However, addressing the original question, its doubtful IMO anyone can detect pedaling differences of 99.58 versus 99.83 percent.

Smoothness and noise reduction probably play into the greater perceived advantage.

[ada@prorider.or]

Smoothness and noise reduction probably play into the greater perceived advantage.

Well then you have to go to steel,since ceramic is harder is also due to this reason more noise!!.

iI doubt some has a full ceramic bearing with high precsion
since its a hell of a job to make the race´s with a high precision and hybrid bearings only have more friction the steel.

[Grant McLean]

Cees,

what difference in watts for bb ceramic hybrid bearings?
I'm sure you've done the calculation. I read 0.4w, is that close?

In a workstand, spinning cranks may be impressive, but don't be fooled!
Friction UNDER LOAD is not the same as drag from the seals of the bearings.
Actual bearing performance is what matters...


-g

[zap]

Get a Phil Wood square taper bb, install your favorite square campy crank, break it in for 10 years, then it will be perfect......for another 10 years.

I find it hard to believe that in a low load, low rpm application that ceramic makes any difference, all else being equal.

If I'm not mistaken, Velonews did a test a year or so ago and found external bb (including some with ceramic hybrid balls) to have higher friction than square tt bb.

[Tobias]

ada, I don't make the bearings, just passing on the reported differences.
BTW, not enough advantage for me to buy at present costs.

"Use of ceramic (silicon nitride) balls in place of steel balls can radically improve bearing performance several ways. Because ceramic balls are 60% lighter than steel balls, and because their surface finish is almost perfectly smooth, they exhibit vibration levels two to seven times lower than conventional steel ball bearings."

[ada@prorider.or]

Cees,
what difference in watts for bb ceramic hybrid bearings?
I'm sure you've done the calculation. I read 0.4w, is that close?



Well normal steel bearing in bike takes about bb and hubs
takes max 2 watts at 50 km/h 100 kg bike and rider
since ceramic hybrid has about 30 % more friction then steel .......

This is from my mind since i published the measurement that i done at philips space lab a while ago .


You have less friction with certain full ceramics bearings
(cost about 1500$ each)

Altough with out load it seems that hybrid bearings are smoother ,but underload then its worse



and that for 0.5 watts ?!!

[ada@prorider.or]

they exhibit vibration levels two to seven times lower than conventional steel ball bearings."


Well vibration is something else as sound!
The harder the material the more sound !