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Non-steel bearings?

Old 12-10-06, 02:45 PM
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Non-steel bearings?

I was reading recently in Bicycling magazine, that these new ceramic (?) bearings really make a difference on racer's bikes. They can count for 1 gear on hills was the estimate. Really, on something as already efficient as a bike, that's a massive improvement, particularly compared to anything else we might have available. Apparently the bearings are really expensive, but if they were durable also, or lower maintenance, maybe it would be worth it. Maybe money spent on something like DT hubs and these bearings would be quantifiably an improvement, where something expensive we take for granted today, like an expensive paintjob on a custom bike is not.

Obviously this only applies to people willing to drop some change, of course cheaper alternatives exist and are perfectly good enough. Just wondering if these bearings would make a difference in our world, or are limited in some respect.
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Old 12-11-06, 12:17 PM
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I think that gain of 1 gear is just plain wrong. A lot of threads on that topic on the mechanics forum, here's a good one:

https://www.bikeforums.net/bicycle-mechanics/231529-ceramic-replacement-bearing-shimano-bbs.html
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Old 12-11-06, 02:17 PM
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Thanks! I hadn't seen that or anything else other than the Bicycling issue on this (pizza issue). I find the arguments in the referenced thread are inconsistant or beneficial to the claim. Inconsistant because they assume the bicycle science book is good or still valid science, who knows. For instance there is less argument over square end BB resistance improvements than the bearings improvement though either is rejectable on the no room for a difference argument.

Also the improvements seem all to run our way, we tend to be heavy, slow and interested in max power output, all factors that make the argument weaker for racers than tourers. Stuff like light oil would not hold up so well in our case.

The interesting thing about the B. article/new stuff collumn perhaps (didn't really read it) is that it is based on pro rider experiences. As long as the usual lying sales agent factor isn't intruding (what hope), this should be an easily verified program. Good riders could easily spot an improvement in performance if it exists, and amounted to anything like a gear. It's a real world thing, not based on some jig and some scenario. I notice my bike rolls a lot better at the outset of a trip. Imagine a stainless chain and better bearings, less gumming up as the tour proceeds.

Best thing about the thread is it's assessment of square taper BBS.
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Old 12-11-06, 04:37 PM
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I also engaged in an argument concerning these bearings - they are slightly lighter and slightly rounder than the equivilent steel bearings.

So what? You still put them into deformed bottom brackets or wheel hubs that are far less round than the bearing tolerances which effective cancel any gains.

Hey, if you're racing you do these sorts of things because a hundred small changes like that MIGHT make the difference.

For real people, standing up on the bike to stretch has already canceled out all of the possible gains from another couple of hundred dollars in bearings.

That guy had it pretty accurate when he said that it was like improving your mileage in your Hummer by upgrading to titanium seatbelt buckles.
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Old 12-11-06, 06:00 PM
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Originally Posted by Peterpan1
Thanks! I hadn't seen that or anything else other than the Bicycling issue on this (pizza issue). I find the arguments in the referenced thread are inconsistant or beneficial to the claim. Inconsistant because they assume the bicycle science book is good or still valid science, who knows.
How is the scientific validity of an article in a flashy racer-boy monthly bicycling magazine that does not cite sources or offer scientific evidence in favor of the claims made about ceramic bearings a safer bet than the validity of a book that does these things AND can and does take the time and space to explain all of these things? Answer: it's NOT a safer bet. It's a good book, and it gives readers a lot more reason to believe the claims made in the book (that is, actual experimental results and CORRECT mathematics and physical science data that back up claims that are only hypothetical) than that Bicycling article gives. Ceramic bearings give a benefit of one gear because someone wants to sell you ceramic bearings. Listen to the folks in that thread, they are right on the money. A racer wouldn't notice the effect of ceramic bearings, which make a negligible contribution to drag on a bicycle. On a touring bike, it would be an absurd joke. Ceramic bearings are pointless, invisible bling for any cyclist. It would be that much more absurd on a slow, plodding touring bike out to see the sights and experience a little bit of adventure.
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Old 12-11-06, 08:28 PM
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"How is the scientific validity of an article in a flashy racer-boy monthly bicycling magazine that does not cite sources or offer"

Well the beauty is they don't claim to be be scientific. Its obviously subjective. I don't even have the mag, And I am not claiming it is authoritative, I am merely asking whether it coming to be accepted as true. I don't recall whether they site sources or not.

"scientific evidence in favor of the claims made about ceramic bearings"

Of course social science type experiments are probably funded by as much money as any. Advertising, focus groups, propaganda etc... It would be reasonably possible to lie to a bunch of riders in an artful way so as to try to get good feedback on bearings without them knowing what the real issue was. Or it may just be a "whadaya think" kind of deal. As you say useless, which I think I already mentioned the possibility of.

"a safer bet than the validity of a book that does these things AND can and does take the time and space to explain all of these things?"

I'm sorry I didn't realize the book had investigated claims about these new bearings. What I took the above argument to be was that they accepted, in the thread, the book as authoritative, which depending on the currency of the information could be like taking talbot's word for something relating to carbon frames. The idea that the bearing never accounts for significant drag is ridiculous on the face of it. It's only true if the bearings are being perfectly maintained by a race mechanic. I would love to have the way my bike sails along on fresh everything last longer than a day or two. If it was possible. Touring is not a perfect bike with factory mechanics. And spares available every race. So who knows. I mean people don't think Phil bearings/hubs at a significant upcharge are pattently ridiculous and ruled out by some book.

"Answer: it's NOT a safer bet. It's a good book, and it gives readers a lot more reason to believe the claims made in the book (that is, actual experimental results and CORRECT mathematics and physical science data that back up claims that are only hypothetical) than that Bicycling article gives."

Well science is all about some specific set of test criteria. One is not free, within the parameters of science, to just slap any old set of results over any old other set of circumstances. My point was not, in anay case, about the validity of the book but the uncritical way it was pulled into the thread/argument. I'm certainly aware of the desire of people to sell stuff, including bearings, the strained currency of certain studies, or their own technical expertise. Stores are open 24 hours a day.

>

"So what? You still put them into deformed bottom brackets or wheel hubs that are far less round than the bearing tolerances which effective cancel any gains."

Good luck with cancelling the gains. That's like saying if you are riding down a rough road, with an equally out of round wheel, no advantage is to be had from a true wheel, since all the bumps just cancel each other out... nice world to live in. Now if the wheel is only .001" out of true then there isn't anything much to going to .0005".


Without going on, I would say these bearings have not been designed for the cycling industry, presumably they have some serious application. Now wheter it is tranferable here is the whole question. Wouldn't it be nice if someone had some actual experience of them in touring conditions. Let's try the freebee test? If we weren't just squaring off, which bearings would you take for free, ceramic or steel, up to you, you can have all the free bearings you want of either type, but only for your own use. So far I don't know the answer.
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Old 12-11-06, 09:38 PM
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Subjective measurements of improved performance can't be trusted. Period. Too much "sugar pill" effect, to great a likelihood of other factors being the real cause of improvement. The point is that there is no reason to believe that there would be a noticeable difference between ceramic bearings and traditional steel bearings in bicycle applications.

The bearings themselves, by the way, do not contribute significant drag. Get on a bike with gummy, crunchy hub bearings and see how fast you can pedal. I bet that you can easily get fast enough for wind resistance to be far more important. I've never ridden bearings so bad that you can't easily attain that kind of speed on a bike. And even with the bottom bracket on my racing bike being shot, I can't tell any difference between it and the perfect, new bottom bracket on my touring bike when I'm turning the pedals. And, in fact, I can still get the racing bike to higher speeds, thanks to better aerodynamics. Once you have a big heavy (relative to the bike) person on a bicycle, the effect of gummy, high-drag bearings just doesn't amount to a hill of beans.

But this is a non-issue anyway. A well maintained bike, heck, any bike that isn't simply ignored, will have relatively free-turning, low friction bearings. That's what we're comparing, right? A poorly maintained, gummy ol' bearing with ceramic bearing balls is still going to roll like crap. Maintenance isn't the issue here, the issue is whether, given equivalent levels of care and maintenance, a ceramic bearing will cause an objectively significant difference in the amount of effort required to move a bicycle at a given speed. The answer here is "probably not." You need a significantly greater change in the system than just the material in order to make a difference. Really smooth up against narsty, sticky old bearings? Maybe. Ceramic vs. steel bearing balls? I find it hard to believe that a tiny increase in hardness and tolerances could make a difference that a human being could possibly detect.

You are correct in believing that ceramic bearings were not originally designed for the bicycle industry. I don't know for certain, but I suspect that they were developed for high-performance automobiles or other mechanical uses where bearings are placed under a high degree of stress and must spin at extremely high speeds. The loads put on bicycle bearings are extremely low! Ceramic bearings could make a very real difference in durability and performance when used under the kinds of conditions that the bearings in most engines and powered vehicles are subjected to. For the tiny loads that bicycle bearings have to deal with, it just isn't going to be worth the expense.
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