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Old 10-18-09, 04:15 PM   #1
MChristenson
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Replacing steel bearings with Ceramic - general question

Hi all,

I'm new here and not an experienced mechanic. I have 7 year old Trek 7300 adult bike that has seen some miles and I am beginning to replace some components.

In my reading (Sheldon Brown etc etc) I have come across the amazing factoid (?) that Ceramic bearings in the Bottom bracket can reduce total rolling friction from 4% to 0.5 percent. I have also read that (generally) loose balls are better than balls in a retainer, AND that light oil can (or should?) be used with ceramic Bearings. Finally I have also read that there are ceramic / ceramic races and balls but also there is a hybrid of ceramic balls with steel races.

OK, here's my beginner, probably too dumb to be worthy of a polite response, question -

What happens if somebody were to replace the steel bearings with high grade equivalent ceramic bearings?

I'm a tourist, the bike can use some further replacements, so I'm willing to take a chance, but then I don't want to do something just outright stupid....

What's the experience or best conjecture on doing such a thing? Certainly this has been tried? Perhaps some shops are doing it routinely already? Conversely if a mechanic were to do this would it be considered unorthodox or an outright mistake?

Also regarding the other bearings on a bike, would this also be true for hub bearings?

Regarding rolling friction I thought perhaps I could somehow measure before and after by doing something like fastening a known weight to the crank at 3:00, letting the crank "drop" then counting the number of turns the rear wheel makes maybe 5 times and averaging - before and after. If there is a significant change in friction this should give some measure of it?

Will appreciate any comments on this whole idea of substituting ceramic for steel into existing and lightly worn races.


Sincerely,

Michael

(My very first post ever here....)
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Old 10-18-09, 04:24 PM   #2
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In my reading (Sheldon Brown etc etc) I have come across the amazing factoid (?) that Ceramic bearings in the Bottom bracket can reduce total rolling friction from 4% to 0.5 percent.
Huh? that's contrary to what I've read. Any links? Is this the same Sheldon Brown that wrote this about ceramic bearings?:

Most bearing balls are super-hard steel. Lately, some suppliers have been promoting very expensive bearings that use ceramic balls.
These are a silly gimmick, aimed at gullible cyclists with too much money. They have no real benefit in practical use on bicycles.
"A fool and his money are soon parted."
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Old 10-18-09, 04:32 PM   #3
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What happens if somebody were to replace the steel bearings with high grade equivalent ceramic bearings?
First, welcome to the forum and, no, it's not a dumb question.

The brief answer to your question is that ceramic bearings are a tremendously expensive answer to a question nearly nobody asked. They do reduce friction in components with nearly no friction to begin with and do it at great cost. The Pros use them because their sponsors are paying for them but the real advantage even to them is almost zero.

As a tourist, keep your hubs and bottom bracket clean, well lubed and properly adjusted and use good quality steel bearings. You will never ever see any advantage to ceramic bearings over good quality steel ones but your wallet will thank you.

And, yes. loose balls instead of retainer held balls are slightly better since a few more balls will fit in the race and share the load over more bearings. Here, the cost penalty is about zero.
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Old 10-18-09, 04:48 PM   #4
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You have to decide whether or not ceramic bearings is worth the extra outlay. Ceramic bearings for other applications are often OEM packed with grease, so I don't know where that 'use light oil' comes from unless you are racing short distances or have a BB oil port and don't mind adding/checking oil levels frequently.

If the grease you are currently using is too tacky, then use another brand of grease or buy an NLGI 1 or 1.5 grease. This will make a bigger difference than ceramic bearings.
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Old 10-18-09, 05:14 PM   #5
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Waste of time even thinking about it.

If you wanted that miniscule advantage you'd be best to avoid the hybrid ceramic bearings which offer no advantage. With ceramic it's all or nothing. If you're not racing and your bike isn't worth at least $6k+, ceramic is a waste of money.
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Old 10-18-09, 05:28 PM   #6
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If you're not racing and your bike isn't worth at least $6k+, ceramic is a waste of money.
My take is that even if both of these things are true, you are wasting your money.
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Old 10-18-09, 05:35 PM   #7
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My take is that even if both of these things are true, you are wasting your money.
It's not.

The psychological advantage sometimes is enough to be useful, whether it makes you 0.00001% faster or 0.0000000000000001% faster. WR events have their own special preparation but they're guaranteed to be using ceramic.
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Old 10-18-09, 05:41 PM   #8
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Wow, thanks! 3 responses already. Amazing site/community here....

Here are a few further notes on where things came from:

1. The 4% steel versus as low as 0.5% for ceramic came from a Cycling news article Sept 14, 2006 - titled "WIll this new bottom Bracket make you faster?" H

2. No, Sheldon Brown certainly did not recommend and I certainly didn't mean to imply he did. The note about using loose balls came from him in a paragraph that pointed out that retainers are useful to manufacturers for assembly and to save cost be dropping a bearing (or two?).

3. There are various sources for individual ceramic bearings at prices that seem very close to steel to me - I might be missing something (like minimum order size/ shipping) but I'm thinking rather general anyway.


My impression of the overall situation is that between technology transfer, reduced sales overall, and new web based sources (bless them) that the price for (I believe first quality - but this is making some assumptions) Ceramic individual bearings have dropped significantly for the average Joe. I think I will do more research but a quick google of sources for loose ceramic bearings has given me a number of sources for a bag of 10 ceramic 0.250 Dia bearings for from 19 to 25USD.

Here I'll snip in their description:

Pack of 10 Loose Ceramic Balls 1/4 inch 6.35mm Si3N4, Grade-5 quality balls, this is a popular size that could be used in many Bicycle, or any application that uses this size 1/4 Inch. Balls are made of Ceramic Si3N4.
  • Item: Loose Balls
  • Size: 1/4 Inch = 6.35mm
  • Quality: Grade 5
  • Material: Ceramic
  • Quantity: 10 Loose Balls.
According to the Wheels Mnfg site :
  • Grade 5 Si3N4 bearings are twice as hard as steel bearings
  • 70% stiffer, 75% smoother, 60% lighter

Does that change anything already said?

I'm a bit of a "armchair mechanic" and I enjoy keeping track of the shifting edge of these things.

So does the above price and information change things?

Also, I guess, I'd like to hear about "worse case" / possible problems.....

Thanks so much, I'm learning!

Michail
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Old 10-18-09, 05:47 PM   #9
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It doesn't.

You really aren't going to gain any benefit from ceramic for a performance hybrid. You are literally burning money. You'd be better off spending that extra money on high quality high TPI tyres (this WILL make you faster) inflated properly and/or a professional bike fit instead.

I can't stress how irrelevant bearing resistance is on a properly maintained high quality loose ball hubs (you'd be an idiot to put those on crappy hubs).
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Old 10-18-09, 06:09 PM   #10
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If you're tourist, or even a sport rider, your best bet is to get a sealed BB, be it shimano, phil, or one of the others. Then you get less friction than an open BB and low to no maintenance.
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Old 10-18-09, 07:44 PM   #11
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If you're tourist, or even a sport rider, your best bet is to get a sealed BB, be it shimano, phil, or one of the others. Then you get less friction than an open BB and low to no maintenance.
This is opposite of reality.

Loose ball bbs that came with last generations bikes have significantly less drag than modern shimano carts/phil carts with phil bearings. Even a $2 loose ball bb can be adjusted to spin more than a shimano cart. External bb systems are even worse.
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Old 10-18-09, 07:53 PM   #12
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The actual amount of drag from the BB is so miniscule (relative to total drag) that saving any of that drag is insignificant. So let's say a BB saps 4-seconds from you in a 100-mile ride. Reducing that loss to 0.5-seconds isn't really that huge of a savings. For example, it's not going to be the difference between 25th and 1st in a race.
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Old 10-18-09, 08:06 PM   #13
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. There are various sources for individual ceramic bearings at prices that seem very close to steel to me.....

Ceramic individual bearings have dropped significantly for the average Joe. I think I will do more research but a quick google of sources for loose ceramic bearings has given me a number of sources for a bag of 10 ceramic 0.250 Dia bearings for from 19 to 25USD.....
Does that change anything already said?
No, it doesn't change anything. A package of 10 1/4" ceramic balls for $20 is no where near close to good quality steel bearings. First, you will need two packages for a typical rear hub so the bearing balls alone will be $40 plus shipping.

For comparison, Grade 25 (very high quality) 1/4" chrome-steel bearing balls are less than $5 in packages of 100. Here is a source: http://www.loosescrews.com/index.cgi...d=964320116153

So the penalty is $35 for NO useful benefit.

operator's comment about the psychological benefit is correct and the comment about current record events always using ceramic bearings is also correct but someone else is paying for them, not the rider.
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Old 10-18-09, 08:34 PM   #14
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The actual amount of drag from the BB is so miniscule (relative to total drag) that saving any of that drag is insignificant. So let's say a BB saps 4-seconds from you in a 100-mile ride. Reducing that loss to 0.5-seconds isn't really that huge of a savings. For example, it's not going to be the difference between 25th and 1st in a race.
This is not correct. It's the amount of watts the BB takes. You can be certain this is significant with a well adjusted loose ball bb vs an external system. If you've seen both of these, campy record square taper vs, record "ultra torque" - you'll agree with me without argument.
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Old 10-18-09, 08:54 PM   #15
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This is not correct. It's the amount of watts the BB takes. You can be certain this is significant with a well adjusted loose ball bb vs an external system. If you've seen both of these, campy record square taper vs, record "ultra torque" - you'll agree with me without argument.
link/pic?
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Old 10-18-09, 09:06 PM   #16
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link/pic?
Only a video can show you this.
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Old 10-19-09, 12:00 AM   #17
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This is opposite of reality.

Loose ball bbs that came with last generations bikes have significantly less drag than modern shimano carts/phil carts with phil bearings. Even a $2 loose ball bb can be adjusted to spin more than a shimano cart. External bb systems are even worse.
Hey you know op, your right...in your world of perfectly square and aligned bottom bracket bracket faces and use of frictionless grease.

For the rest of us in reality however where we might not want to oil bathe our bottom brackets... your wrong.
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Old 10-19-09, 12:56 AM   #18
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1. The 4% steel versus as low as 0.5% for ceramic came from a Cycling news article Sept 14, 2006 - titled "WIll this new bottom Bracket make you faster?" H
You have to understand where this "knowledge" comes from. Journalists typically know next to nothing about what they're reporting on. They re-write what some else has told them. In 2006 ceramic bearings are just entering the market. The only source of data is the people selling the bearings. The "facts" of the article are probably a direct swipe from a press release. Swallow with several grams of salt.




Bicycling magazine, for instance, places vendor data ahead of common sense.
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Old 10-19-09, 01:16 AM   #19
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Bear in mind also, cheap ceramic bearings are often machined(is this even the word for ceramics) to lower tolerances than comparably priced steel bearings. You pay more for an inferior product.
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Old 10-19-09, 01:30 AM   #20
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This is not correct. It's the amount of watts the BB takes. You can be certain this is significant with a well adjusted loose ball bb vs an external system. If you've seen both of these, campy record square taper vs, record "ultra torque" - you'll agree with me without argument.
Are you talking about the study Jobst Brandt did a couple of years ago comparing a Campy Record versus an FSA Megaexo?

I would also think that the rubber seals on the bearings would represent more drag than the difference between steel vs. ceramic bearings. Or even the difference in shear-friction between running grease versus oil.
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Old 10-19-09, 07:33 AM   #21
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I haven't seen anyone yet point out that even if you use bearings that are absolutely perfectly spherical, you are still spinning them in between cups and an axle that are unlikely to be ground and polished to anything close to a tolerance that could take advantage of such a bearing.

Which is why good ceramic bearings come in a cartridge that is designed around the bearing.

I personally think ceramic bearings make sense in derailleur pulleys-the fastest spinning bearings on a bike, then hubs. My DT 240s feel amazing with Enduro ceramic bearings in them, but as far as BBs go, they spin too slowly to make the kind of difference worth paying for....
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Old 10-19-09, 08:25 AM   #22
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My DT 240s feel amazing with Enduro ceramic bearings in them, but as far as BBs go, they spin too slowly to make the kind of difference worth paying for....
My Campy Chorus and Shimano Dura Ace hubs with the stock steel balls also feel "amazing". They will "pendulum" for a dozen cycles as the very slight wheel imbalance settles to the bottom after I hang the bikes on their storage racks. How much energy could these possibly absorb at riding speeds? If ceramic bearings cut the losses to zero, the difference on the road would be immeasurable.
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Old 10-19-09, 09:04 AM   #23
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I haven't seen anyone yet point out that even if you use bearings that are absolutely perfectly spherical, you are still spinning them in between cups and an axle that are unlikely to be ground and polished to anything close to a tolerance that could take advantage of such a bearing.
Off topic a little, but since the parts that ride on the bearings are not of high tolerance, would it matter if i installed Grade 25 or Grade 200 ball bearings?
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Old 10-19-09, 09:48 AM   #24
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Off topic a little, but since the parts that ride on the bearings are not of high tolerance, would it matter if i installed Grade 25 or Grade 200 ball bearings?
The races are really pretty good on most hubs and Grade 25 balls (the much higher grade ones) sell for so small a premium over Grade 200 that they are well worth using.
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Old 10-19-09, 10:18 AM   #25
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I personally think ceramic bearings make sense in derailleur pulleys-the fastest spinning bearings on a bike, then hubs. My DT 240s feel amazing with Enduro ceramic bearings in them, but as far as BBs go, they spin too slowly to make the kind of difference worth paying for....
The bolded statements makes very little sense. Bottom bracket bearings see the highest loads of any bearing on a bike whereas derailler pulley bearings see basically zero load (hence why most deraillers have simple bushings instead of bearings). Better bearings make a difference under heavy load. Almost any bearing can be adjusted to feel decent at zero load. I can agree with hubs possibly benefiting from ceramics but again only because they see such (relatively) high loads.
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