Re: A problem with gears.

Dave Kahn

On Wed, 15 Dec 2004 17:13:49 +0000, JLB <JLB@bigbad.demon.co.uk>
wrote:

>Your statement "I still don't believe that load is a significant
>factor in chain wear" suggests you refuse to accept basic mechanical
>engineering knowledge.

It might suggest that except for the fact that you conveniently cut
four words from the end of my statement. What I actually said was, "I
still don't believe that load is a significant factor in chain wear in
normal bicycle riding."

--
Dave...

Get a bicycle. You will not regret it. If you live. - Mark Twain

JLB

Dave Kahn wrote:
> On Wed, 15 Dec 2004 17:13:49 +0000, JLB <JLB@bigbad.demon.co.uk>
> wrote:
>
>
>>Your statement "I still don't believe that load is a significant
>>factor in chain wear" suggests you refuse to accept basic mechanical
>>engineering knowledge.
>
>
> It might suggest that except for the fact that you conveniently cut
> four words from the end of my statement. What I actually said was, "I
> still don't believe that load is a significant factor in chain wear in
> normal bicycle riding."
>
Fine. Put it back in. And explain what the difference is between a
bicycle chain in normal bicycle riding and a mechanical system of
components subject to conventional well-known tribological wear
mechanisms. If you can't, you are still pissing into the wind.

--
Joe * If I cannot be free I'll be cheap

David Martin

On 16/12/04 12:03 am, in article cpqjc8$ahr$1$8302bc10@news.demon.co.uk,
"JLB" <JLB@bigbad.demon.co.uk> wrote:

> Dave Kahn wrote:
>> On Wed, 15 Dec 2004 17:13:49 +0000, JLB <JLB@bigbad.demon.co.uk>
>> wrote:
>>
>>
>>> Your statement "I still don't believe that load is a significant
>>> factor in chain wear" suggests you refuse to accept basic mechanical
>>> engineering knowledge.
>>
>>
>> It might suggest that except for the fact that you conveniently cut
>> four words from the end of my statement. What I actually said was, "I
>> still don't believe that load is a significant factor in chain wear in
>> normal bicycle riding."
>>
> Fine. Put it back in. And explain what the difference is between a
> bicycle chain in normal bicycle riding and a mechanical system of
> components subject to conventional well-known tribological wear
> mechanisms. If you can't, you are still pissing into the wind.

The arguement is not over whether load is a factor, it clearly is, but over
the significance of the load.

Which variable would have most effect on the chain wear rate? High load or
high dirt?

At which point we gather lots of data and start to evaluate them with
respect to wear rate.

If you ignore the dirt on the chain, what is the correlation between load
and wear? (R = x)

If you ignore the load on the chain, what is the correlation between dirt
and wear? (R = y)

Now, if y is much bigger than x (much closer to 1) then I would clearly
have to support the statement that dirt is significantly more important wrt
chain wear than load.

Data anyone?

...d

JLB

David Martin wrote:
> On 16/12/04 12:03 am, in article cpqjc8$ahr$1$8302bc10@news.demon.co.uk,
> "JLB" <JLB@bigbad.demon.co.uk> wrote:
>
>
>>Dave Kahn wrote:
>>
>>>On Wed, 15 Dec 2004 17:13:49 +0000, JLB <JLB@bigbad.demon.co.uk>
>>>wrote:
>>>
>>>
>>>
>>>>Your statement "I still don't believe that load is a significant
>>>>factor in chain wear" suggests you refuse to accept basic mechanical
>>>>engineering knowledge.
>>>
>>>
>>>It might suggest that except for the fact that you conveniently cut
>>>four words from the end of my statement. What I actually said was, "I
>>>still don't believe that load is a significant factor in chain wear in
>>>normal bicycle riding."
>>>
>>
>>Fine. Put it back in. And explain what the difference is between a
>>bicycle chain in normal bicycle riding and a mechanical system of
>>components subject to conventional well-known tribological wear
>>mechanisms. If you can't, you are still pissing into the wind.
>
>
> The arguement is not over whether load is a factor, it clearly is, but over
> the significance of the load.

The original statement said load was not significant, which is absurd.
You have changed the debate.
>
> Which variable would have most effect on the chain wear rate? High load or
> high dirt?

The chain will wear if there is load even with no dirt whatsoever,
because the lubrication of a bicycle chain will in practice not be
perfect. Whenever the steel components make contact and there is any
normal force there will be wear. The wear will produce particles that
will themselves accelerate the rate of wear.
>
> At which point we gather lots of data and start to evaluate them with
> respect to wear rate.
>
> If you ignore the dirt on the chain, what is the correlation between load
> and wear? (R = x)
>
> If you ignore the load on the chain, what is the correlation between dirt
> and wear? (R = y)

There might even be a point where there is so much dirt it decreases the
rate of wear by providing a better spread of load and therefore lower
stresses across the chain components.
>
> Now, if y is much bigger than x (much closer to 1) then I would clearly
> have to support the statement that dirt is significantly more important wrt
> chain wear than load.
>
> Data anyone?

No. Zebedee has had enough.


--
Joe * If I cannot be free I'll be cheap

David Martin

On 16/12/04 12:57 am, in article cpqmhh$roc$1$8300dec7@news.demon.co.uk,
"JLB" <JLB@bigbad.demon.co.uk> wrote:

> David Martin wrote:
>> On 16/12/04 12:03 am, in article cpqjc8$ahr$1$8302bc10@news.demon.co.uk,
>> "JLB" <JLB@bigbad.demon.co.uk> wrote:
>>
>>
>>> Dave Kahn wrote:
>>>
>>>> On Wed, 15 Dec 2004 17:13:49 +0000, JLB <JLB@bigbad.demon.co.uk>
>>>> wrote:
>>>>
>>>>
>>>>
>>>>> Your statement "I still don't believe that load is a significant
>>>>> factor in chain wear" suggests you refuse to accept basic mechanical
>>>>> engineering knowledge.
>>>>
>>>>
>>>> It might suggest that except for the fact that you conveniently cut
>>>> four words from the end of my statement. What I actually said was, "I
>>>> still don't believe that load is a significant factor in chain wear in
>>>> normal bicycle riding."
>>>>
>>>
>>> Fine. Put it back in. And explain what the difference is between a
>>> bicycle chain in normal bicycle riding and a mechanical system of
>>> components subject to conventional well-known tribological wear
>>> mechanisms. If you can't, you are still pissing into the wind.
>>
>>
>> The arguement is not over whether load is a factor, it clearly is, but over
>> the significance of the load.
>
> The original statement said load was not significant, which is absurd.
> You have changed the debate.

It is not a change in the debate. Load having no effect is very different to
load having a significant role.

Significant in this case is relative to other factors. If dirt relates to
chain wear very well, but load poorly (evne though in the controlled
environment when the other factors are constant there is a clear linear
relationship) the load is not a *significant* factor.

>> Which variable would have most effect on the chain wear rate? High load or
>> high dirt?
>
> The chain will wear if there is load even with no dirt whatsoever,
> because the lubrication of a bicycle chain will in practice not be
> perfect. Whenever the steel components make contact and there is any
> normal force there will be wear. The wear will produce particles that
> will themselves accelerate the rate of wear.

Of course it will. This misses the point though. The point is how fast this
occurs and whether external dirt is significant in dramatically accelerating
the process.

>>
>> At which point we gather lots of data and start to evaluate them with
>> respect to wear rate.
>>
>> If you ignore the dirt on the chain, what is the correlation between load
>> and wear? (R = x)
>>
>> If you ignore the load on the chain, what is the correlation between dirt
>> and wear? (R = y)
>
> There might even be a point where there is so much dirt it decreases the
> rate of wear by providing a better spread of load and therefore lower
> stresses across the chain components.

Indeed. We can all speculate. Easy to do in the absence of data. (how many
angels on the head of that pin?)

>>
>> Now, if y is much bigger than x (much closer to 1) then I would clearly
>> have to support the statement that dirt is significantly more important wrt
>> chain wear than load.
>>
>> Data anyone?
>
> No. Zebedee has had enough.

Boingggg!

Time for bed.

...d

Dave Kahn

On Thu, 16 Dec 2004 01:17:23 +0000, David Martin
<d.m.a.martin@dundee.ac.uk> wrote:

>Boingggg!
>
>Time for bed.

WHS

--
Dave...

Get a bicycle. You will not regret it. If you live. - Mark Twain

JLB

David Martin wrote:
> On 16/12/04 12:57 am, in article cpqmhh$roc$1$8300dec7@news.demon.co.uk,
> "JLB" <JLB@bigbad.demon.co.uk> wrote:
>>David Martin wrote:
>>>On 16/12/04 12:03 am, in article cpqjc8$ahr$1$8302bc10@news.demon.co.uk,
>>>"JLB" <JLB@bigbad.demon.co.uk> wrote:
>>>>Dave Kahn wrote:
>>>>>On Wed, 15 Dec 2004 17:13:49 +0000, JLB <JLB@bigbad.demon.co.uk>
>>>>>wrote:
>>>>>>Your statement "I still don't believe that load is a significant
>>>>>>factor in chain wear" suggests you refuse to accept basic mechanical
>>>>>>engineering knowledge.

>>>>>It might suggest that except for the fact that you conveniently cut
>>>>>four words from the end of my statement. What I actually said was, "I
>>>>>still don't believe that load is a significant factor in chain wear in
>>>>>normal bicycle riding."

>>>>Fine. Put it back in. And explain what the difference is between a
>>>>bicycle chain in normal bicycle riding and a mechanical system of
>>>>components subject to conventional well-known tribological wear
>>>>mechanisms. If you can't, you are still pissing into the wind.

>>>The arguement is not over whether load is a factor, it clearly is, but over
>>>the significance of the load.

>>The original statement said load was not significant, which is absurd.
>>You have changed the debate.
>
> It is not a change in the debate. Load having no effect is very different to
> load having a significant role.

Which bit of "I still don't believe that load is a significant factor in
chain wear in normal bicycle riding." are you struggling with? Either
load is significant, in which case the belief is wrong, or load is
insignificant, in which case the belief is right.
>
> Significant in this case is relative to other factors.

No it is not. No load = no wear. Nothing in the relevant statement talks
about relevant to other factors, and even if it did it would be wrong,
because those other factors cannot produce any wear in the absence of
load. Load is necessary before there can be any wear and wear rates
increase as load increases. How can that not be significant?

If dirt relates to
> chain wear very well, but load poorly (evne though in the controlled
> environment when the other factors are constant there is a clear linear
> relationship) the load is not a *significant* factor.

See subsequent cites.

>>>Which variable would have most effect on the chain wear rate? High load or
>>>high dirt?

This is not the question. Dirt matters. However, it is absurd to suggest
that load is insignificant because load is necessary before there can be
any wear and wear rates increase as load increases.
>>
>>The chain will wear if there is load even with no dirt whatsoever,
>>because the lubrication of a bicycle chain will in practice not be
>>perfect. Whenever the steel components make contact and there is any
>>normal force there will be wear. The wear will produce particles that
>>will themselves accelerate the rate of wear.
>
> Of course it will. This misses the point though. The point is how fast this
> occurs and whether external dirt is significant in dramatically accelerating
> the process.

This is not the question. Th point is it is absurd to suggest that load
is insignificant because load is necessary before there can be any wear
and wear rates increase as load increases

>>>At which point we gather lots of data and start to evaluate them with
>>>respect to wear rate.

Tribologists have been doing this for quite a while. It is one of the
reasons we can be confident load is significant because it is necessary
for there to be load before there can be any wear and wear rates
increase as load increases

>>>If you ignore the dirt on the chain, what is the correlation between load
>>>and wear? (R = x)

>>>If you ignore the load on the chain, what is the correlation between dirt
>>>and wear? (R = y)

>>There might even be a point where there is so much dirt it decreases the
>>rate of wear by providing a better spread of load and therefore lower
>>stresses across the chain components.
>
> Indeed. We can all speculate. Easy to do in the absence of data. (how many
> angels on the head of that pin?)
>
See the cites and note how load is included in every one as a
significant factor.

Remember: the debate is whether it is reasonable to believe load is not
significant.

>>>Now, if y is much bigger than x (much closer to 1) then I would clearly
>>>have to support the statement that dirt is significantly more important wrt
>>>chain wear than load.
>>>Data anyone?

Some cites

http://www.whitfordww.com/design/wear.html
http://www.tribology-abc.com/abc/wear.htm
http://www.machinerylubrication.com...roup=WearDebris

It's all good stuff. For example, on the machinerylubrication webpage,
Fig. 1 is a handy summary of the rrecongnised wear mechanisms and how
they are influenced by certain variables. Note that one parameter is
hardness/load. Wear is slower with harder materials; wear is faster with
increased load. Then note that the horizontal axis is logarithmic, which
is a hint that the rate at which wear increases can be quite dramatic.
However, even if it is merely linear, there is no shadow or scintilla of
doubt that load is significant because it is necessary for there to be
load before there can be any wear and wear rates increase as load increases.
--
Joe * If I cannot be free I'll be cheap

David Martin

On 16/12/04 1:36 pm, in article cps300$6p$1$8300dec7@news.demon.co.uk, "JLB"
<JLB@bigbad.demon.co.uk> wrote:

> David Martin wrote:
>> On 16/12/04 12:57 am, in article cpqmhh$roc$1$8300dec7@news.demon.co.uk,
>> "JLB" <JLB@bigbad.demon.co.uk> wrote:
>>> David Martin wrote:
>>>> On 16/12/04 12:03 am, in article cpqjc8$ahr$1$8302bc10@news.demon.co.uk,
>>>> "JLB" <JLB@bigbad.demon.co.uk> wrote:
>>>>> Dave Kahn wrote:
>>>>>> On Wed, 15 Dec 2004 17:13:49 +0000, JLB <JLB@bigbad.demon.co.uk>
>>>>>> wrote:
>>>>>>> Your statement "I still don't believe that load is a significant
>>>>>>> factor in chain wear" suggests you refuse to accept basic mechanical
>>>>>>> engineering knowledge.
>
>>>>>> It might suggest that except for the fact that you conveniently cut
>>>>>> four words from the end of my statement. What I actually said was, "I
>>>>>> still don't believe that load is a significant factor in chain wear in
>>>>>> normal bicycle riding."
>
>>>>> Fine. Put it back in. And explain what the difference is between a
>>>>> bicycle chain in normal bicycle riding and a mechanical system of
>>>>> components subject to conventional well-known tribological wear
>>>>> mechanisms. If you can't, you are still pissing into the wind.
>
>>>> The arguement is not over whether load is a factor, it clearly is, but over
>>>> the significance of the load.
>
>>> The original statement said load was not significant, which is absurd.
>>> You have changed the debate.
>>
>> It is not a change in the debate. Load having no effect is very different to
>> load having a significant role.
>
> Which bit of "I still don't believe that load is a significant factor in
> chain wear in normal bicycle riding." are you struggling with? Either
> load is significant, in which case the belief is wrong, or load is
> insignificant, in which case the belief is right.
>>
>> Significant in this case is relative to other factors.
>
> No it is not. No load = no wear. Nothing in the relevant statement talks
> about relevant to other factors, and even if it did it would be wrong,
> because those other factors cannot produce any wear in the absence of
> load. Load is necessary before there can be any wear and wear rates
> increase as load increases. How can that not be significant?
>
> If dirt relates to
>> chain wear very well, but load poorly (evne though in the controlled
>> environment when the other factors are constant there is a clear linear
>> relationship) the load is not a *significant* factor.
>
> See subsequent cites.
>
>>>> Which variable would have most effect on the chain wear rate? High load or
>>>> high dirt?
>
> This is not the question. Dirt matters. However, it is absurd to suggest
> that load is insignificant because load is necessary before there can be
> any wear and wear rates increase as load increases.
>>>
>>> The chain will wear if there is load even with no dirt whatsoever,
>>> because the lubrication of a bicycle chain will in practice not be
>>> perfect. Whenever the steel components make contact and there is any
>>> normal force there will be wear. The wear will produce particles that
>>> will themselves accelerate the rate of wear.
>>
>> Of course it will. This misses the point though. The point is how fast this
>> occurs and whether external dirt is significant in dramatically accelerating
>> the process.
>
> This is not the question. Th point is it is absurd to suggest that load
> is insignificant because load is necessary before there can be any wear
> and wear rates increase as load increases


Let me phrase that differently. A change in load may be insignificant in
respect to a change in maintenance and cleanliness of the chain.

The age of the rider is, by your arguement, also significant because with no
rider there is no wear. Silly arguement. The whole debate hinges on whether
variations in load are better predictors for variations in chain wear than
variations in chain cleanliness.

>>>> At which point we gather lots of data and start to evaluate them with
>>>> respect to wear rate.
>
> Tribologists have been doing this for quite a while. It is one of the
> reasons we can be confident load is significant because it is necessary
> for there to be load before there can be any wear and wear rates
> increase as load increases

indeed they do. And the relationship is extremely well modelled if you keep
conditions constant (ie same amount of dirt, lubrication etc.)

>
>>>> If you ignore the dirt on the chain, what is the correlation between load
>>>> and wear? (R = x)
>
>>>> If you ignore the load on the chain, what is the correlation between dirt
>>>> and wear? (R = y)
>
>>> There might even be a point where there is so much dirt it decreases the
>>> rate of wear by providing a better spread of load and therefore lower
>>> stresses across the chain components.
>>
>> Indeed. We can all speculate. Easy to do in the absence of data. (how many
>> angels on the head of that pin?)
>>
> See the cites and note how load is included in every one as a
> significant factor.
>
> Remember: the debate is whether it is reasonable to believe load is not
> significant.

but they all refer to the same system. Taking a population of cyclists, will
load be a significant predictor of chain wear? Will dirt be a significant
predictor of chain wear? WIll lubrication be a significant predictor of
chain wear?

>
> Some cites
>
> http://www.whitfordww.com/design/wear.html
> http://www.tribology-abc.com/abc/wear.htm
> http://www.machinerylubrication.com...d=468&relatedbo
> okgroup=WearDebris
>
> It's all good stuff. For example, on the machinerylubrication webpage,
> Fig. 1 is a handy summary of the rrecongnised wear mechanisms and how
> they are influenced by certain variables. Note that one parameter is
> hardness/load.

It is indeed for fatigue and adhesion modes of wear. It is not mentioned for
abrasive wear, wheras teh main focus of the abrasive wear is the nature and
size of contaminant particles in teh lubricant, ie the dirt.

> Wear is slower with harder materials; wear is faster with
> increased load. Then note that the horizontal axis is logarithmic, which
> is a hint that the rate at which wear increases can be quite dramatic.

Indeed. And in the situations described, ie a bicycle chain, the wear mode
is most likely to be abrasive or corrosive. It is far less likely to be
adhesive.

> However, even if it is merely linear, there is no shadow or scintilla of
> doubt that load is significant because it is necessary for there to be
> load before there can be any wear and wear rates increase as load increases.

It is about realtive rates of increase. If <handwave> wear increases
linearly with load, but abrasion increases exponentially, load will not be
significant compared to changes in the nature of the dirt in the
lubricant</handwave>


Which is the most important factor for bicycle chains, load or dirt?

...d

JLB

David Martin wrote:
> On 16/12/04 1:36 pm, in article cps300$6p$1$8300dec7@news.demon.co.uk, "JLB"
> <JLB@bigbad.demon.co.uk> wrote:
>
>
>>David Martin wrote:
>>
>>>On 16/12/04 12:57 am, in article cpqmhh$roc$1$8300dec7@news.demon.co.uk,
>>>"JLB" <JLB@bigbad.demon.co.uk> wrote:
>>>
>>>>David Martin wrote:
>>>>
>>>>>On 16/12/04 12:03 am, in article cpqjc8$ahr$1$8302bc10@news.demon.co.uk,
>>>>>"JLB" <JLB@bigbad.demon.co.uk> wrote:
>>>>>
>>>>>>Dave Kahn wrote:
>>>>>>
>>>>>>>On Wed, 15 Dec 2004 17:13:49 +0000, JLB <JLB@bigbad.demon.co.uk>
>>>>>>>wrote:
>>>>>>>
>>>>>>>>Your statement "I still don't believe that load is a significant
>>>>>>>>factor in chain wear" suggests you refuse to accept basic mechanical
>>>>>>>>engineering knowledge.
>>
>>>>>>>It might suggest that except for the fact that you conveniently cut
>>>>>>>four words from the end of my statement. What I actually said was, "I
>>>>>>>still don't believe that load is a significant factor in chain wear in
>>>>>>>normal bicycle riding."
>>
>>>>>>Fine. Put it back in. And explain what the difference is between a
>>>>>>bicycle chain in normal bicycle riding and a mechanical system of
>>>>>>components subject to conventional well-known tribological wear
>>>>>>mechanisms. If you can't, you are still pissing into the wind.
>>
>>>>>The arguement is not over whether load is a factor, it clearly is, but over
>>>>>the significance of the load.
>>
>>>>The original statement said load was not significant, which is absurd.
>>>>You have changed the debate.
>>>
>>>It is not a change in the debate. Load having no effect is very different to
>>>load having a significant role.
>>
>>Which bit of "I still don't believe that load is a significant factor in
>>chain wear in normal bicycle riding." are you struggling with? Either
>>load is significant, in which case the belief is wrong, or load is
>>insignificant, in which case the belief is right.
>>
>>>Significant in this case is relative to other factors.
>>
>>No it is not. No load = no wear. Nothing in the relevant statement talks
>>about relevant to other factors, and even if it did it would be wrong,
>>because those other factors cannot produce any wear in the absence of
>>load. Load is necessary before there can be any wear and wear rates
>>increase as load increases. How can that not be significant?
>>
>>If dirt relates to
>>
>>>chain wear very well, but load poorly (evne though in the controlled
>>>environment when the other factors are constant there is a clear linear
>>>relationship) the load is not a *significant* factor.
>>
>>See subsequent cites.
>>
>>
>>>>>Which variable would have most effect on the chain wear rate? High load or
>>>>>high dirt?
>>
>>This is not the question. Dirt matters. However, it is absurd to suggest
>>that load is insignificant because load is necessary before there can be
>>any wear and wear rates increase as load increases.
>>
>>>>The chain will wear if there is load even with no dirt whatsoever,
>>>>because the lubrication of a bicycle chain will in practice not be
>>>>perfect. Whenever the steel components make contact and there is any
>>>>normal force there will be wear. The wear will produce particles that
>>>>will themselves accelerate the rate of wear.
>>>
>>>Of course it will. This misses the point though. The point is how fast this
>>>occurs and whether external dirt is significant in dramatically accelerating
>>>the process.
>>
>>This is not the question. Th point is it is absurd to suggest that load
>>is insignificant because load is necessary before there can be any wear
>>and wear rates increase as load increases
>
>
>
> Let me phrase that differently. A change in load may be insignificant in
> respect to a change in maintenance and cleanliness of the chain.
>
> The age of the rider is, by your arguement, also significant because with no
> rider there is no wear. Silly arguement.

Are you being deliberately dim, or deliberately silly?

It does not matter what the source of the load is. Could be this rider,
another rider, bike chain test machine, anything at all; but still it
follows that no load = no wear; and increase in load = increase in wear.

The whole debate hinges on whether
> variations in load are better predictors for variations in chain wear than
> variations in chain cleanliness.

No. The statement was "I still don't believe that load is a significant
factor in chain wear in normal bicycle riding." Show me the bit of that
statement that says anything about "better predictors". Explain how the
load can be other than significant.

>
>>>>>At which point we gather lots of data and start to evaluate them with
>>>>>respect to wear rate.
>>
>>Tribologists have been doing this for quite a while. It is one of the
>>reasons we can be confident load is significant because it is necessary
>>for there to be load before there can be any wear and wear rates
>>increase as load increases
>
>
> indeed they do. And the relationship is extremely well modelled if you keep
> conditions constant (ie same amount of dirt, lubrication etc.)
>
>
>>>>>If you ignore the dirt on the chain, what is the correlation between load
>>>>>and wear? (R = x)
>>
>>>>>If you ignore the load on the chain, what is the correlation between dirt
>>>>>and wear? (R = y)
>>
>>>>There might even be a point where there is so much dirt it decreases the
>>>>rate of wear by providing a better spread of load and therefore lower
>>>>stresses across the chain components.
>>>
>>>Indeed. We can all speculate. Easy to do in the absence of data. (how many
>>>angels on the head of that pin?)
>>>
>>
>>See the cites and note how load is included in every one as a
>>significant factor.
>>
>>Remember: the debate is whether it is reasonable to believe load is not
>>significant.
>
>
> but they all refer to the same system. Taking a population of cyclists, will
> load be a significant predictor of chain wear? Will dirt be a significant
> predictor of chain wear? WIll lubrication be a significant predictor of
> chain wear?

Why don't you find out if you want to know? What is indisputable is that
load is significant.
>
>
>>Some cites
>>
>>http://www.whitfordww.com/design/wear.html
>>http://www.tribology-abc.com/abc/wear.htm
>>http://www.machinerylubrication.com...d=468&relatedbo
>>okgroup=WearDebris
>>
>>It's all good stuff. For example, on the machinerylubrication webpage,
>>Fig. 1 is a handy summary of the recognised wear mechanisms and how
>>they are influenced by certain variables. Note that one parameter is
>>hardness/load.
>
>
> It is indeed for fatigue and adhesion modes of wear. It is not mentioned for
> abrasive wear, wheras teh main focus of the abrasive wear is the nature and
> size of contaminant particles in teh lubricant, ie the dirt.

Did you actually look? There is extensive mention of abrasion. The
specific Fig. 1 that I referred to is a summary of four wear mechanisms,
the first one being "abrasion"; this figure is followed be a whole
section of discussion of abrasion. You might not have spotted it because
it was disguised under the misleading heading "abrasion", which could
have put you off the scent, before you reached Figure 2, which is
described on the page as "Nominal Wear Factors for Abrasive Wear", so
how would anybody realise that had anything to do with abrasive wear?
Apart from that though, and of course corrosion, which is also there,
you almost have a point.
>
>
>>Wear is slower with harder materials; wear is faster with
>>increased load. Then note that the horizontal axis is logarithmic, which
>>is a hint that the rate at which wear increases can be quite dramatic.
>
>
> Indeed. And in the situations described, ie a bicycle chain, the wear mode
> is most likely to be abrasive or corrosive. It is far less likely to be
> adhesive.

And this relates to the question of whether load is significant how?
Also, why rule out adhesive wear? Whenever the lubrication fails to
prevent direct contact of the chain components under load, adhesive wear
will occur. Given how bicycle chains are used and lubricated this is
entirely predictable. This is described in the first cite.
>
>
>>However, even if it is merely linear, there is no shadow or scintilla of
>>doubt that load is significant because it is necessary for there to be
>>load before there can be any wear and wear rates increase as load increases.
>
>
> It is about realtive rates of increase. If <handwave> wear increases
> linearly with load, but abrasion increases exponentially, load will not be
> significant compared to changes in the nature of the dirt in the
> lubricant</handwave>

Even if your handwave was true concerning the relationship of wear to
the various factors the conclusion would still be false. It is as absurd
as arguing that for a simple DC circuit where you are interested in the
amount of current you can declare that voltage matters but resistance is
simply not significant.
>
>
> Which is the most important factor for bicycle chains, load or dirt?

This is not the question being addressed. Load is significant. It is
necessary for there to be load before there can be any wear and wear
rates increase as load increases. That's not merely significant, it's
fundamental. There's no point in even thinking about understanding wear
unless you are going to allow the significance of load.

--
Joe * If I cannot be free I'll be cheap

Clive George

"JLB" <JLB@bigbad.demon.co.uk> wrote in message
news:cpshpq$miq$1$8300dec7@news.demon.co.uk...

> > but they all refer to the same system. Taking a population of cyclists,
will
> > load be a significant predictor of chain wear? Will dirt be a
significant
> > predictor of chain wear? WIll lubrication be a significant predictor of
> > chain wear?
>
> Why don't you find out if you want to know? What is indisputable is that
> load is significant.

How significant? Not as much as muck, which is what I suspect David is
saying.

cheers,
clive

JLB

Clive George wrote:
> "JLB" <JLB@bigbad.demon.co.uk> wrote in message
> news:cpshpq$miq$1$8300dec7@news.demon.co.uk...
>
>
>>>but they all refer to the same system. Taking a population of cyclists,
>
> will
>
>>>load be a significant predictor of chain wear? Will dirt be a
>
> significant
>
>>>predictor of chain wear? WIll lubrication be a significant predictor of
>>>chain wear?
>>
>>Why don't you find out if you want to know? What is indisputable is that
>>load is significant.
>
>
> How significant? Not as much as muck, which is what I suspect David is
> saying.

Quite possibly, but that's a separate argument. Dave Kahn posted:
"I still don't believe that load is a significant factor in chain wear
in normal bicycle riding."
I 'm trying to get across the point that load is significant in
determining chain wear. Wear will only occur if there is a load, and the
rate of wear will increase if the load increases. That makes load
significant. That's all. That is the whole of the message. I've said
what I want to say on this subject. Load is significant. End.


--
Joe * If I cannot be free I'll be cheap

James Annan

JLB wrote:

> Load is necessary before there can be any wear and wear rates
> increase as load increases. How can that not be significant?

Even I'm starting to find this level of pedantry rather childish.

As David Martin explained in detail, if all other factors are held
constant, then two riders with strength/weight/hillinesss/gearing or
whatever will wear out chains at a different rate according to the loads
they generate. However, if one rider has a clean chain and the other a
dirty one, this will almost certainly overwhelm all other differences.
I'm sure that is all the original claim was meant to imply, and I think
that saying "load is not a significant factor in normal use" is an
entirely reasonable shorthand for it.

James
--
If I have seen further than others, it is
by treading on the toes of giants.
http://www.ne.jp/asahi/julesandjames/home/

JLB

James Annan wrote:
> JLB wrote:
>
>> Load is necessary before there can be any wear and wear rates
>> increase as load increases. How can that not be significant?
>
>
> Even I'm starting to find this level of pedantry rather childish.
>
> As David Martin explained in detail, if all other factors are held
> constant, then two riders with strength/weight/hillinesss/gearing or
> whatever will wear out chains at a different rate according to the loads
> they generate. However, if one rider has a clean chain and the other a
> dirty one, this will almost certainly overwhelm all other differences.
> I'm sure that is all the original claim was meant to imply, and I think
> that saying "load is not a significant factor in normal use" is an
> entirely reasonable shorthand for it.

Only to the psychic. As it stands it is plain wrong.


--
Joe * If I cannot be free I'll be cheap

David Martin

JLB wrote:
> David Martin wrote:

>>
>>> Some cites
>>>
>>> http://www.whitfordww.com/design/wear.html
>>> http://www.tribology-abc.com/abc/wear.htm
>>> http://www.machinerylubrication.com...d=468&relatedbo
>>>
>>> okgroup=WearDebris
>>>
>>> It's all good stuff. For example, on the machinerylubrication webpage,
>>> Fig. 1 is a handy summary of the recognised wear mechanisms and how
>>> they are influenced by certain variables. Note that one parameter is
>>> hardness/load.
>>
>>
>>
>> It is indeed for fatigue and adhesion modes of wear. It is not
>> mentioned for
>> abrasive wear, wheras teh main focus of the abrasive wear is the
>> nature and
>> size of contaminant particles in teh lubricant, ie the dirt.
>
>
> Did you actually look?

Obviously more carefully than you.

> There is extensive mention of abrasion. The
> specific Fig. 1 that I referred to is a summary of four wear mechanisms,
> the first one being "abrasion"; this figure is followed be a whole
> section of discussion of abrasion. You might not have spotted it because
> it was disguised under the misleading heading "abrasion", which could
> have put you off the scent, before you reached Figure 2, which is
> described on the page as "Nominal Wear Factors for Abrasive Wear", so
> how would anybody realise that had anything to do with abrasive wear?
> Apart from that though, and of course corrosion, which is also there,
> you almost have a point.

Oh, very funny. Now, your starter for ten is to find *any* mention of
the load being significant in abrasive wear on that page. The three
significant factors listed are:
Particle size, particle hardness and particle density. No mention of
load at all except obliquely as 'load-bearing surface'.

Now, returning to figure 1. Which mode of wear is most significant by
several orders of magnitude. Why, it is abrasion!


>>> Wear is slower with harder materials; wear is faster with
>>> increased load. Then note that the horizontal axis is logarithmic, which
>>> is a hint that the rate at which wear increases can be quite dramatic.
>>
>>
>>
>> Indeed. And in the situations described, ie a bicycle chain, the wear
>> mode
>> is most likely to be abrasive or corrosive. It is far less likely to be
>> adhesive.
>
>
> And this relates to the question of whether load is significant how?

because the cites you gave do not indicate load as significant in
abrasive wear, and abrasive wear is indicated as the major component of
wear.

> Also, why rule out adhesive wear? Whenever the lubrication fails to
> prevent direct contact of the chain components under load, adhesive wear
> will occur. Given how bicycle chains are used and lubricated this is
> entirely predictable. This is described in the first cite.

fair enough, and load will be a factor in this. Still with a potential
of several orders of magnitude less than dirt though.

>
>>
>>
>>> However, even if it is merely linear, there is no shadow or scintilla of
>>> doubt that load is significant because it is necessary for there to be
>>> load before there can be any wear and wear rates increase as load
>>> increases.
>>
>>
>>
>> It is about realtive rates of increase. If <handwave> wear increases
>> linearly with load, but abrasion increases exponentially, load will
>> not be
>> significant compared to changes in the nature of the dirt in the
>> lubricant</handwave>
>
>
> Even if your handwave was true concerning the relationship of wear to
> the various factors the conclusion would still be false. It is as absurd
> as arguing that for a simple DC circuit where you are interested in the
> amount of current you can declare that voltage matters but resistance is
> simply not significant.
>
>

Not the same at all. Given the option of reducing load or reducing
contaminants in the lubrication, it appears from the cites you ahve
given that far more can be done to reduce wear by reducing the contaminants.


>
>>
>> Which is the most important factor for bicycle chains, load or dirt?
>
>
> This is not the question being addressed.

Yes it is. The arguement was over whether it was increased load or
increased dirt that was primarily responsible for shortening the lives
of cycle chains.

> Load is significant. It is
> necessary for there to be load before there can be any wear and wear
> rates increase as load increases. That's not merely significant, it's
> fundamental. There's no point in even thinking about understanding wear
> unless you are going to allow the significance of load.

We are arguing cross purposes here. I am obviously using a different
meaning of significant to you.

You are using significant in the strict sense of 'has to be present'.

I am using it in the sense of 'changes in this parameter are most
closely related to changes in the effect under study'

Think of my version of significant as 'principal component'.

And so, the arguement can be rephrased as:

Dirt is the prinicpal component affecting chain wear. Load is a minor
but necessary component.


...d