What exactly will happen if your hubs have a little play?
12-07-17, 01:27 PM
#51
Senior Member
...it's magical when you get it right. 
...now you're just making stuff up. If anything, a bicycle wheel most resembles the application in your reference that I have bolded in your quote from it. As to definitions, that's exactly why I've been asking for references in this thread since it started.
Nothing anyone writes here is going to have much effect on how things get done IRL, but it would be nice if we could occasionally have an informed discussion in here on topics that have some real world research and answers without the butthurt that inevitably follows in defense of positions that might be based on something else.
But why would we want to change longstanding tradition at this point, eh ?
...now you're just making stuff up. If anything, a bicycle wheel most resembles the application in your reference that I have bolded in your quote from it. As to definitions, that's exactly why I've been asking for references in this thread since it started.
Nothing anyone writes here is going to have much effect on how things get done IRL, but it would be nice if we could occasionally have an informed discussion in here on topics that have some real world research and answers without the butthurt that inevitably follows in defense of positions that might be based on something else.
But why would we want to change longstanding tradition at this point, eh ?
If you think that, then go a head and preload your wheel as much as you like. Preloading is not what you think btw. You are redefining the term, but I already commented on that. What you are doing is adjusting very close to zero while calling it "preload". The other guy does this as well.
12-07-17, 01:32 PM
#52
Calamari Marionette Ph.D
Many motorcycle road racing teams don't use computer rigs to balance there wheels when replacing tires. They use a simple balancing stand and let gravity tell them where to add weight. The stand has cones that are run into the bearings to stabilize the wheel. The cones MUST be set to eliminate all slop (AKA light preload) in order to accurately balance the wheel. Sometimes those wheels pendulum for what becomes a patience taxing LONG time. Seemingly taking forever to stop. And often, when they finally come to rest, it's only a few grams that have kept them teeter-tottering.
Last edited by SquidPuppet; 12-07-17 at 01:35 PM.
12-07-17, 01:39 PM
#53
Senior Member
Interference is when there is binding. Snug to the point that the adjustment is interfering with efficient operation. That is the definition of too much, or incorrect, or poorly adjusted preload.
Correct preload is exactly what it says. Before load. Peload does not mean loaded or tight. It simply means that clearances have been adjusted out.
Correct Preload = zero play. Eliminating clearances is the literal definition of being preloaded.
Correct Preload does not = tight/binding/interfering.
I agree with SKF here, and it sounds like a bicycle application to me. We don't want wobbly wheels or headsets. And we certainly want slopless crank operation.
I agree here as well, and this sounds a lot like a bicycle application too.
Actual preload is a matter of degrees, ranging from light (and it's many benefits) to excessive and it's destructive consequences.
When we buy and install a brand new cartridge bottom bracket it has zero play. That is because it has been set with a light preload at the factory. Later in it's service life the bottom bracket will exhibit some play or slop. It is worn and that has caused a loss of it's preload. AKA it's toast.
Correct preload is exactly what it says. Before load. Peload does not mean loaded or tight. It simply means that clearances have been adjusted out.
Correct Preload = zero play. Eliminating clearances is the literal definition of being preloaded.
Correct Preload does not = tight/binding/interfering.
I agree with SKF here, and it sounds like a bicycle application to me. We don't want wobbly wheels or headsets. And we certainly want slopless crank operation.
I agree here as well, and this sounds a lot like a bicycle application too.
Actual preload is a matter of degrees, ranging from light (and it's many benefits) to excessive and it's destructive consequences.
When we buy and install a brand new cartridge bottom bracket it has zero play. That is because it has been set with a light preload at the factory. Later in it's service life the bottom bracket will exhibit some play or slop. It is worn and that has caused a loss of it's preload. AKA it's toast.
12-07-17, 01:41 PM
#54
Calamari Marionette Ph.D
Oh OK, LOL :-P
If you think that, then go a head and preload your wheel as much as you like. Preloading is not what you think btw. You are redefining the term, but I already commented on that. What you are doing is adjusting very close to zero while calling it "preload". The other guy does this as well.
If you think that, then go a head and preload your wheel as much as you like. Preloading is not what you think btw. You are redefining the term, but I already commented on that. What you are doing is adjusting very close to zero while calling it "preload". The other guy does this as well.
12-07-17, 01:44 PM
#55
Calamari Marionette Ph.D
I cant be bothered doing the word definition dance. If you think, like the other guy, that a bicycle wheel is anything like a lathe, mill or car whell or ... , then fine, but rally this debate is getting silly. You are now resorting to hyperbole and redefining common engineering terms to act as if you still have a leg to stand on. Any one else can look up the literature for them selves or believe what they read on the forums.
12-07-17, 02:04 PM
#57
Calamari Marionette Ph.D
12-07-17, 06:16 PM
#58
Senior Member
That makes no sense. "Inteference" is almost the definition of preload. That is, Preload is the opposite of clearance. Also the post I replied to claimed a wheel should be both free spinning under the weight of the valve(!) but be preloaded as well ... This sounds suspiciously like having your cake and eating it too.
Trouble with "internet quote war" is that there is an inherent bias to searching certain terms like "bearing preload". Try searching for "bearing clearance" instead. Then you get this (SKF):
Bearings must have the appropriate operating clearance to operate satisfactorily (→ Importance of selecting correct clearance/preload).
In most cases, bearings require a certain degree of clearance (→ Selecting internal clearance). However, in some cases, they may require preload (i.e. negative clearance → Selecting preload).
As a general rule:
Ball bearings should have an operating clearance that is virtually zero.
Cylindrical, needle, spherical and CARB toroidal roller bearings typically require at least a small operational clearance.
Tapered roller and angular contact ball bearings should have a small operational clearance, except in applications where a high degree of stiffness or positional control is required, in which case they can be mounted with a degree of preload.
Selecting internal clearance or preload
or you can read the SKF catalog that has a lot if interesting info:
"Clearance versus preload
For most applications, bearings operate with
some residual clearance. Normally, a positive
operating clearance near zero is the optimum
(† diagram 2).
A somewhat greater clearance may be more
suitable for:
• high-speed applications to reduce frictional
heat
• form errors on the shaft or housing seat
such as ovality
The initial internal clearance prior to mounting
and permissible reduction after mounting, depend
on the type and size of the bearing. The
reduction in clearance due to an interference
fit may require greater initial internal clearance
than Normal to avoid preloading the
bearing († fig. 15, page 167).
Preload (negative operating clearance) has
advantages, but can also be risky. If a high degree
of stiffness is required, light preload can
be suitable († Bearing preload, page 214).
A light preload may also be required when
there is a very light or no external load on the
bearing in operation.
However, there is a risk that too much
preload causes the bearing to overheat, which
further increases preload, friction and heat.
This cycle can continue until the bearing
seizes.
It could be argued that preload is acceptable,
provided the bearing operates in a zone that
does not exceed light preload († diagram 2,
zone between 0 and –1). In this case, however,
there is an increase in friction and frictional
heat.
Although all bearing types can run with some
preload, SKF recommends a positive operating
clearance. This is particularly important for
roller bearings such as cylindrical roller, needle
roller, spherical roller and CARB toroidal roller
bearings."
https://www.google.dk/url?sa=t&rct=j...tHGX9qtuKpVRpv
Page ~212.
What Im getting at is that yeah, preload is "a thing", but none of the applications that require actual preload has much resemblance to bicycle wheels and usually preload is employed for a variety of reasons other than bearing longevity. Anybody can make up their own mind as to how much, or little, or none, they want to preload their wheel bearings, but claiming bearings should always be preloaded is patently false even if you operate with novel definitions of "preload".
Trouble with "internet quote war" is that there is an inherent bias to searching certain terms like "bearing preload". Try searching for "bearing clearance" instead. Then you get this (SKF):
Bearings must have the appropriate operating clearance to operate satisfactorily (→ Importance of selecting correct clearance/preload).
In most cases, bearings require a certain degree of clearance (→ Selecting internal clearance). However, in some cases, they may require preload (i.e. negative clearance → Selecting preload).
As a general rule:
Ball bearings should have an operating clearance that is virtually zero.
Cylindrical, needle, spherical and CARB toroidal roller bearings typically require at least a small operational clearance.
Tapered roller and angular contact ball bearings should have a small operational clearance, except in applications where a high degree of stiffness or positional control is required, in which case they can be mounted with a degree of preload.
Selecting internal clearance or preload
or you can read the SKF catalog that has a lot if interesting info:
"Clearance versus preload
For most applications, bearings operate with
some residual clearance. Normally, a positive
operating clearance near zero is the optimum
(† diagram 2).
A somewhat greater clearance may be more
suitable for:
• high-speed applications to reduce frictional
heat
• form errors on the shaft or housing seat
such as ovality
The initial internal clearance prior to mounting
and permissible reduction after mounting, depend
on the type and size of the bearing. The
reduction in clearance due to an interference
fit may require greater initial internal clearance
than Normal to avoid preloading the
bearing († fig. 15, page 167).
Preload (negative operating clearance) has
advantages, but can also be risky. If a high degree
of stiffness is required, light preload can
be suitable († Bearing preload, page 214).
A light preload may also be required when
there is a very light or no external load on the
bearing in operation.
However, there is a risk that too much
preload causes the bearing to overheat, which
further increases preload, friction and heat.
This cycle can continue until the bearing
seizes.
It could be argued that preload is acceptable,
provided the bearing operates in a zone that
does not exceed light preload († diagram 2,
zone between 0 and –1). In this case, however,
there is an increase in friction and frictional
heat.
Although all bearing types can run with some
preload, SKF recommends a positive operating
clearance. This is particularly important for
roller bearings such as cylindrical roller, needle
roller, spherical roller and CARB toroidal roller
bearings."
https://www.google.dk/url?sa=t&rct=j...tHGX9qtuKpVRpv
Page ~212.
What Im getting at is that yeah, preload is "a thing", but none of the applications that require actual preload has much resemblance to bicycle wheels and usually preload is employed for a variety of reasons other than bearing longevity. Anybody can make up their own mind as to how much, or little, or none, they want to preload their wheel bearings, but claiming bearings should always be preloaded is patently false even if you operate with novel definitions of "preload".
Bottom Bracket Bearing adjustment by Jobst Brandt
Wheel Bearing adjustment by Jobst Brandt
12-07-17, 08:32 PM
#60
Calamari Marionette Ph.D
Yeah, he wouldn't know much, since he was a mechanical engineer for Porsche. 
Chris King vs Racing Dan
Campagnolo vs Racing Dan
Shimano vs Racing Dan
LMAO
Chris King vs Racing Dan
Chris King hubs feature adjustable bearing preload. The bearings should be kept in proper
adjustment for optimum product performance. Do not allow the adjustment to become
loose, as this may cause a loss of performance and could lead to damage to the hubs.
adjustment for optimum product performance. Do not allow the adjustment to become
loose, as this may cause a loss of performance and could lead to damage to the hubs.
Head set. This is accomplished by isolating the thrust force that passes through the steerer tube from the bearing race that provides the radial force that preloads the headset bearing adjustment
9. Install the preload cap and adjusting bolt
into the top of the steerer tube. Then adjust
the headset by tightening the adjusting bolt so
that the fork rotates freely but without play.
See Fig. 7.
10. After adjusting the headset bearing
preload, adjust the stem to the correct
position and tighten the stem fixing bolts
into the top of the steerer tube. Then adjust
the headset by tightening the adjusting bolt so
that the fork rotates freely but without play.
See Fig. 7.
10. After adjusting the headset bearing
preload, adjust the stem to the correct
position and tighten the stem fixing bolts
LMAO
Last edited by SquidPuppet; 12-07-17 at 08:39 PM.
12-07-17, 08:38 PM
#61
Senior Member
Just laugh, but remember to breathe. We were talking about wheels. Bicycle wheels that is.
Im sure, if you look hard enough, you can find some bicycle wheel company that will instruct preloading their bearings, but that does not change the fact the one of, if not THE largest bearing company in the world, as a general rule recommends to NOT preloading bearings. Again read #48.
Im sure, if you look hard enough, you can find some bicycle wheel company that will instruct preloading their bearings, but that does not change the fact the one of, if not THE largest bearing company in the world, as a general rule recommends to NOT preloading bearings. Again read #48.
Last edited by Racing Dan; 12-07-17 at 08:48 PM.
12-07-17, 08:42 PM
#62
Calamari Marionette Ph.D
12-07-17, 08:47 PM
#63
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...you're taking an SKF publication that covers the vast world of bearings, most of which see much different and more intensive uses than bicycle wheel bearings, and selecting out from it whatever seems to agree with your POV.
I've already pointed this out to you once, but what the hell, let's go into infinite loop mode.
I've already pointed this out to you once, but what the hell, let's go into infinite loop mode.
12-07-17, 08:55 PM
#64
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Oh OK, LOL :-P
If you think that, then go a head and preload your wheel as much as you like. Preloading is not what you think btw. You are redefining the term, but I already commented on that. What you are doing is adjusting very close to zero while calling it "preload". The other guy does this as well.
If you think that, then go a head and preload your wheel as much as you like. Preloading is not what you think btw. You are redefining the term, but I already commented on that. What you are doing is adjusting very close to zero while calling it "preload". The other guy does this as well.
...I know exactly what preload means by every common definition of the term.
But yes, this is indeed the source of the differing opinions here. You're using it in a way that I have not seen it used before, for whatever reason. It references the adjustment of a bearing so that all the clearance disappears, and increasing preload then continues to apply some interference to the fit so that friction in the bearing assembly increases.
If you want to leave some slpop in your bearing adjustments (and many do), far be it from me to convince you otherwise. You've probably been doing it a long time. There's just no real, good, documentable reason for doing so in either a bicycle wheel bearing or a headset bearing (which is a different application, but one where I've also been told in this forum "better too loose than too tight." )
It's just bad information, that's been around forever. I don't know where it originated, but this is a forum that claims some expertise in the area, so we ought to pride ourselves on giving out the best information we can.
Bicycles will work either way. It's not a particularly demanding use for bearings in general, and bearing technology is pretty advanced in terms of using them for a low level application like bikes.
12-07-17, 08:56 PM
#65
Senior Member
Sorry I hurt your feelings by giving you a lesson. Im sure you didnt learn anything though and will continue forever quoting your bicycle mechanic guru.
12-07-17, 09:06 PM
#66
Senior Member
...I know exactly what preload means by every common definition of the term.
But yes, this is indeed the source of the differing opinions here. You're using it in a way that I have not seen it used before, for whatever reason. It references the adjustment of a bearing so that all the clearance disappears, and increasing preload then continues to apply some interference to the fit so that friction in the bearing assembly increases.
If you want to leave some slpop in your bearing adjustments (and many do), far be it from me to convince you otherwise. You've probably been doing it a long time. There's just no real, good, documentable reason for doing so in either a bicycle wheel bearing or a headset bearing (which is a different application, but one where I've also been told in this forum "better too loose than too tight." )
It's just bad information, that's been around forever. I don't know where it originated, but this is a forum that claims some expertise in the area, so we ought to pride ourselves on giving out the best information we can.
Bicycles will work either way. It's not a particularly demanding use for bearings in general, and bearing technology is pretty advanced in terms of using them for a low level application like bikes.
But yes, this is indeed the source of the differing opinions here. You're using it in a way that I have not seen it used before, for whatever reason. It references the adjustment of a bearing so that all the clearance disappears, and increasing preload then continues to apply some interference to the fit so that friction in the bearing assembly increases.
If you want to leave some slpop in your bearing adjustments (and many do), far be it from me to convince you otherwise. You've probably been doing it a long time. There's just no real, good, documentable reason for doing so in either a bicycle wheel bearing or a headset bearing (which is a different application, but one where I've also been told in this forum "better too loose than too tight." )
It's just bad information, that's been around forever. I don't know where it originated, but this is a forum that claims some expertise in the area, so we ought to pride ourselves on giving out the best information we can.
Bicycles will work either way. It's not a particularly demanding use for bearings in general, and bearing technology is pretty advanced in terms of using them for a low level application like bikes.
12-07-17, 10:49 PM
#67
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Stop acting as if if the difference between clearance, clearance near zero and preload is not immediately understandable. Its not about opinion and Im not the one with the novel definition. You are. You can go argue with the engineers at SKF as to how much or little "clearance" (not slop) you want to leave.
12-07-17, 11:36 PM
#70
Full Member
true
bearings and cones don't normally contact each other. All bearing actually roll/slide on oil or grease. First the lubricant fails (or washes out/melts out) and THEN metal on metal destroys itself. I take all the slack out then back it off until smooth spin is achieved. Preload has to be extreme to be an issue.
12-08-17, 12:07 AM
#71
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That is: load of a single ball in a preloaded bearing, once a bearing is loaded, does not increase due to the bearing having preload - compared to a bearing with no preload. Preload enables better load distribution over more than one ball and smoother rolling.
Last edited by Bike Gremlin; 12-08-17 at 02:26 AM.
12-08-17, 09:38 AM
#72
Calamari Marionette Ph.D
Not argument - more a question, so correct me if I'm wrong. For all I know friction in a loaded bearing that is properly (optimally) preoloaded doesn't increase compared to a bearing that isn't preloaded.
That is: load of a single ball in a preloaded bearing, once a bearing is loaded, does not increase due to the bearing having preload - compared to a bearing with no preload. Preload enables better load distribution over more than one ball and smoother rolling.
That is: load of a single ball in a preloaded bearing, once a bearing is loaded, does not increase due to the bearing having preload - compared to a bearing with no preload. Preload enables better load distribution over more than one ball and smoother rolling.
12-08-17, 09:54 AM
#73
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Not argument - more a question, so correct me if I'm wrong. For all I know friction in a loaded bearing that is properly (optimally) preoloaded doesn't increase compared to a bearing that isn't preloaded.
That is: load of a single ball in a preloaded bearing, once a bearing is loaded, does not increase due to the bearing having preload - compared to a bearing with no preload. Preload enables better load distribution over more than one ball and smoother rolling.
That is: load of a single ball in a preloaded bearing, once a bearing is loaded, does not increase due to the bearing having preload - compared to a bearing with no preload. Preload enables better load distribution over more than one ball and smoother rolling.
...it's an open question, that has no single properly phrased answer. Bearings differ in terms of design, purpose, and use (obviously). Some of those uses are unique in their requirements. So "optimal" preload (or clearance for that matter) can differ according to that use. For example, a heat related bearing failure on a bicycle is nonexistent for all practical purpose, but more common in stuff like electric motors.
But yeah, in my understanding, a bicycle wheel bearing in correct adjustment ( which has just a tiny bit more preload than none at all) will create such minimal increase in friction as to be of no concern. And that minimal increase is justified by the better loading distribution you get on the bearings. Which in theory ought to extend the life of the assembly somewhat.
All of this assumes a quality bearing assembly to begin with (races ground and aligned to decent tolerances, and hardened) and regular maintenance. IME the bulk of the bearing failures in bicycles are maintenance related, and I honestly have not personally witnessed many that appeared to be related to adjustment.
If bearing adjustment were all that critical, you'd expect to see much more evidence of failures resulting from either too much play or not enough clearance. I've seen and worked on a lot of bikes in the later stages of their lifespan, and that does not appear to be common. But I'm not doing engineering analysis, I'm only going from experience and observation. In their treatment of bike bearings, even Bicycling Science goes toward the idea that the common old school cup and cone bearing assembly for bicycles is probably over engineered.
12-08-17, 09:57 AM
#74
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12-08-17, 10:11 AM
#75
Calamari Marionette Ph.D
I just want to make sure I have all the facts cleared up so that I can leave this thread properly educated.
1. Chris King recommends a light preload on their wheel and headset bearings.
2. Campagnolo recommends a light preload on their wheel and headset bearings.
3. Shimano recommends a light preload on all their bearings.
4. A mechanical engineer explained why a light preload on bicycle wheel bearings reduces drag and extends the life of the ball and tracks via increased load bearing surface area and efficient grease distribution.
5. A mechanical engineer explained why a bicycle wheel bearing with clearance between the balls and tracks will have increased drag and a reduced life span.
5. SKF, a leading bearing manufacturer says "Preload has advantages".
6. Sealed cartridge bicycle bottom brackets come with bearings that have been preloaded by the manufacturer.
7. Racing Dan says preload is bad for bicycle wheel bearings and will prevent the wheel from rolling freely.
OK. Gotcha. Thanks for the lesson.
Last edited by SquidPuppet; 12-08-17 at 10:18 AM.