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ceramic bearings
Just installed ceramic bearings in my front wheel. The original
bearings seem much smoother. Is this just because the ceramics are not broke in? They just don't seem as smooth as the bearings I took out. I ended up putting the originals back in for now. Any info would be appreciated. Thanks. Rick "We don't slow down because we get old. We get old because we slow down." --------- __o ------- _`\,_ ------ (*)/ (*) ****************** |
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#2
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ceramic bearings
"Rick Roof" wrote in message ... Just installed ceramic bearings in my front wheel. The original bearings seem much smoother. Is this just because the ceramics are not broke in? If there was a difference in 'smoothness' between steel and ceramic bearings, it would be so infintesimal so as to be immesurable with real equipment. Difference in watts power usage on the bike?? Basically zero. Aerodynamics is many orders of magnitude more important. The only possible positive of ceramics is that they may survive a little longer in a hub that is contaminated with grit and water. Maybe. But this brings up the bigger question as to why not just appropriately maintain your hubs? An even better solution would be to get a hub that has a grease injection port. Then, maintenance would amount to a minute per year to squeeze some grease into the hub shell and wipe up the old stuff. |
#3
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ceramic bearings
"Dave Mayer" wrote in message news:rxhLj.168159$pM4.160323@pd7urf1no... "Rick Roof" wrote in message ... Just installed ceramic bearings in my front wheel. The original bearings seem much smoother. Is this just because the ceramics are not broke in? If there was a difference in 'smoothness' between steel and ceramic bearings, it would be so infintesimal so as to be immesurable with real equipment. Difference in watts power usage on the bike?? Basically zero. Aerodynamics is many orders of magnitude more important. The only possible positive of ceramics is that they may survive a little longer in a hub that is contaminated with grit and water. Maybe. But this brings up the bigger question as to why not just appropriately maintain your hubs? Agreed An even better solution would be to get a hub that has a grease injection port. That is the second stupiest way to maintain a hub. The first is not to maintain the hub at all. You have to inject a ton of grease to push out the old dirty grease through the seal. Not very healthy for the seal. Choose a hub that is easy (take apart and adjust afterwards) to maintain. Then you maintain it more often. I vote for Campy hubs. Then, maintenance would amount to a minute per year to squeeze some grease into the hub shell and wipe up the old stuff. Lou |
#4
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ceramic bearings
"Lou Holtman" wrote in message
... "Dave Mayer" wrote in message news:rxhLj.168159$pM4.160323@pd7urf1no... "Rick Roof" wrote in message ... Just installed ceramic bearings in my front wheel. The original bearings seem much smoother. Is this just because the ceramics are not broke in? If there was a difference in 'smoothness' between steel and ceramic bearings, it would be so infintesimal so as to be immesurable with real equipment. Difference in watts power usage on the bike?? Basically zero. Aerodynamics is many orders of magnitude more important. The only possible positive of ceramics is that they may survive a little longer in a hub that is contaminated with grit and water. Maybe. But this brings up the bigger question as to why not just appropriately maintain your hubs? Agreed An even better solution would be to get a hub that has a grease injection port. That is the second stupiest way to maintain a hub. The first is not to maintain the hub at all. You have to inject a ton of grease to push out the old dirty grease through the seal. Not very healthy for the seal. Choose a hub that is easy (take apart and adjust afterwards) to maintain. Then you maintain it more often. I vote for Campy hubs. Then, maintenance would amount to a minute per year to squeeze some grease into the hub shell and wipe up the old stuff. Lou I vote for sealed bearing hubs, ie, no maintenance You just ride until they **** themselves, then replace. I haven't had to replace one yet and I have a couple of hubs that have had an absolute kaning (in the mud and water). I cant wait till the XT hubs on my SS die so I can replace them with some nice DT's, then I never ever have to worry about those stupid shimano setups, such a pain to set, especially when I have to replace *yet* another busted freewheel assembly Cheers Dre (talking about mtb hubs here though) |
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ceramic bearings
On Thu, 10 Apr 2008 05:25:43 GMT, "Dave Mayer"
may have said: But this brings up the bigger question as to why not just appropriately maintain your hubs? An even better solution would be to get a hub that has a grease injection port. Then, maintenance would amount to a minute per year to squeeze some grease into the hub shell and wipe up the old stuff. Too much grease increases drag, at least until enough is forced back out for the grease packs to shear and develop gaps. The amount that would be present after pumping in enough to actually repack the bearings would be in that range easily. Pumping in more grease also does not remove the contaminated grease that's already present. Proper maintenance begins with "Clean". -- My email address is antispammed; pull WEEDS if replying via e-mail. Typoes are not a bug, they're a feature. Words processed in a facility that contains nuts. |
#6
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ceramic bearings
In article ,
Werehatrack wrote: On Thu, 10 Apr 2008 05:25:43 GMT, "Dave Mayer" may have said: But this brings up the bigger question as to why not just appropriately maintain your hubs? An even better solution would be to get a hub that has a grease injection port. Then, maintenance would amount to a minute per year to squeeze some grease into the hub shell and wipe up the old stuff. Too much grease increases drag, at least until enough is forced back out for the grease packs to shear and develop gaps. The amount that would be present after pumping in enough to actually repack the bearings would be in that range easily. If you can demonstrate it takes more than seconds of operation for this to happen, I'll be impressed. The first time the bearing is operated, the balls go through the grease like, well, a bunch of bowling balls through soft butter. If grease needs to be displaced for the balls to move, it happens almost immediately. The grease has virtually no ability to resist this displacement. It's also incompressible, and has little propensity to flow or rebound, so it doesn't return to the bearing track except as a thin film. Pumping in more grease also does not remove the contaminated grease that's already present. That's exactly what it does. Typical grease-injection hubs have a port in the hub shell that admits grease into the axle area. the grease can only flow from there through the bearing and then out the seals. When clean grease is coming out of the outer seal, there is no place for contaminated grease to be. You don't have to believe me. Grease-ported hubs are cheap: pump and see. -- Ryan Cousineau http://www.wiredcola.com/ "In other newsgroups, they killfile trolls." "In rec.bicycles.racing, we coach them." |
#7
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ceramic bearings
"Ryan Cousineau" wrote in message ]... In article , Werehatrack wrote: On Thu, 10 Apr 2008 05:25:43 GMT, "Dave Mayer" may have said: But this brings up the bigger question as to why not just appropriately maintain your hubs? An even better solution would be to get a hub that has a grease injection port. Then, maintenance would amount to a minute per year to squeeze some grease into the hub shell and wipe up the old stuff. Too much grease increases drag, at least until enough is forced back out for the grease packs to shear and develop gaps. The amount that would be present after pumping in enough to actually repack the bearings would be in that range easily. If you can demonstrate it takes more than seconds of operation for this to happen, I'll be impressed. The first time the bearing is operated, the balls go through the grease like, well, a bunch of bowling balls through soft butter. If grease needs to be displaced for the balls to move, it happens almost immediately. The grease has virtually no ability to resist this displacement. It's also incompressible, and has little propensity to flow or rebound, so it doesn't return to the bearing track except as a thin film. Pumping in more grease also does not remove the contaminated grease that's already present. That's exactly what it does. Typical grease-injection hubs have a port in the hub shell that admits grease into the axle area. the grease can only flow from there through the bearing and then out the seals. When clean grease is coming out of the outer seal, there is no place for contaminated grease to be. Not true. The pumped in grease seeks the easiest way out. If you see clean grease comming out there is still contaminated grease inside in the hidden corners. You don't have to believe me. Grease-ported hubs are cheap: pump and see. You don't have to believe me either. Lou |
#8
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ceramic bearings
On Fri, 11 Apr 2008 07:08:38 GMT, Ryan Cousineau
may have said: In article , Werehatrack wrote: On Thu, 10 Apr 2008 05:25:43 GMT, "Dave Mayer" may have said: But this brings up the bigger question as to why not just appropriately maintain your hubs? An even better solution would be to get a hub that has a grease injection port. Then, maintenance would amount to a minute per year to squeeze some grease into the hub shell and wipe up the old stuff. Too much grease increases drag, at least until enough is forced back out for the grease packs to shear and develop gaps. The amount that would be present after pumping in enough to actually repack the bearings would be in that range easily. If you can demonstrate it takes more than seconds of operation for this to happen, I'll be impressed. How much are you offering to pay for the bench time? The drag is small, but everything-weenies being what they are, it would matter to them. (Probably nobody else, though.) Choice of grease and design of component might have a lot to do with the clearance time. The first time the bearing is operated, the balls go through the grease like, well, a bunch of bowling balls through soft butter. If grease needs to be displaced for the balls to move, it happens almost immediately. The grease has virtually no ability to resist this displacement. It's also incompressible, and has little propensity to flow or rebound, so it doesn't return to the bearing track except as a thin film. Unless, of course, the entire cavity is filled, in which case the incompressibility means that the balls are running in a viscous semifluid instead of freely. This is one of the reasons why pump-lubed hubs are not as common as they used to be, while aftermarket ball-and-socket joints typically still get supplied with grease fittings. (The big reason, of course, is that with modern lubricants and components, the bearings don't require the frequency of re-lube that old ones needed.) I recall being told that this used to be a topic in MechE studies; point being that one should always allow clearance room for the excess lube to exit. Merely adding a grease fitting to a conventional hub design is not going to meet the spec. Pumping in more grease also does not remove the contaminated grease that's already present. That's exactly what it does. Typical grease-injection hubs have a port in the hub shell that admits grease into the axle area. the grease can only flow from there through the bearing and then out the seals. When clean grease is coming out of the outer seal, there is no place for contaminated grease to be. You've never taken one apart, then? It would be educational. The contaminated grease will be everywhere that wasn't an active loaded surface, and the clean grease will have flowed right past it. You don't have to believe me. Grease-ported hubs are cheap: pump and see. I used to work on them. I'm glad that modern hubs don't have grease fittings. -- My email address is antispammed; pull WEEDS if replying via e-mail. Typoes are not a bug, they're a feature. Words processed in a facility that contains nuts. |
#9
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ceramic bearings
On Apr 9, 9:04 pm, Rick Roof wrote:
Just installed ceramic bearings in my front wheel. The original bearings seem much smoother. Is this just because the ceramics are not broke in? They just don't seem as smooth as the bearings I took out. I ended up putting the originals back in for now. Any info would be appreciated. Thanks. Rick I'm wondering if anyone is going to even remotely answer your question instead of highjacking it for a totally irrelevant discussion. Often the argument starts with at least a disagreement on actual advice. Didn't even get that far! I'm curious about your question so I will stand by (but not hold my breath). |
#10
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ceramic bearings
In article ,
Werehatrack wrote: On Fri, 11 Apr 2008 07:08:38 GMT, Ryan Cousineau may have said: In article , Werehatrack wrote: On Thu, 10 Apr 2008 05:25:43 GMT, "Dave Mayer" may have said: But this brings up the bigger question as to why not just appropriately maintain your hubs? An even better solution would be to get a hub that has a grease injection port. Then, maintenance would amount to a minute per year to squeeze some grease into the hub shell and wipe up the old stuff. Too much grease increases drag, at least until enough is forced back out for the grease packs to shear and develop gaps. The amount that would be present after pumping in enough to actually repack the bearings would be in that range easily. If you can demonstrate it takes more than seconds of operation for this to happen, I'll be impressed. How much are you offering to pay for the bench time? The drag is small, but everything-weenies being what they are, it would matter to them. (Probably nobody else, though.) Choice of grease and design of component might have a lot to do with the clearance time. The first time the bearing is operated, the balls go through the grease like, well, a bunch of bowling balls through soft butter. If grease needs to be displaced for the balls to move, it happens almost immediately. The grease has virtually no ability to resist this displacement. It's also incompressible, and has little propensity to flow or rebound, so it doesn't return to the bearing track except as a thin film. Unless, of course, the entire cavity is filled, in which case the incompressibility means that the balls are running in a viscous semifluid instead of freely. This is one of the reasons why pump-lubed hubs are not as common as they used to be, while aftermarket ball-and-socket joints typically still get supplied with grease fittings. (The big reason, of course, is that with modern lubricants and components, the bearings don't require the frequency of re-lube that old ones needed.) I recall being told that this used to be a topic in MechE studies; point being that one should always allow clearance room for the excess lube to exit. Merely adding a grease fitting to a conventional hub design is not going to meet the spec. Pumping in more grease also does not remove the contaminated grease that's already present. That's exactly what it does. Typical grease-injection hubs have a port in the hub shell that admits grease into the axle area. the grease can only flow from there through the bearing and then out the seals. When clean grease is coming out of the outer seal, there is no place for contaminated grease to be. You've never taken one apart, then? It would be educational. The contaminated grease will be everywhere that wasn't an active loaded surface, and the clean grease will have flowed right past it. Hm... Okay, I have a lot to learn here, but does this apply to Bearing Buddy designs, too? My sense is that at least in the local (rain-dominated) environment, loss of grease is the fundamental killer of bearings. Lots of grease prevents water from getting in. You don't have to believe me. Grease-ported hubs are cheap: pump and see. I used to work on them. I'm glad that modern hubs don't have grease fittings. -- Ryan Cousineau http://www.wiredcola.com/ "In other newsgroups, they killfile trolls." "In rec.bicycles.racing, we coach them." |
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