chain stretch

jds_1981

I'm going to have to agree with Rolf. Once it's worn it can be stretched.
http://dictionary.cambridge.org/diction ... /stretch_4

If a material stretches, it can become longer or wider when pulled and then return to its original size:

So you can easily stretch a worn chain, but not a none-worn one.

meanredspider

jds_1981 wrote:

So you can easily stretch a worn chain, but not a none-worn one.

And you can shrink it to. It will also curve far more too. It's worn

And referring to a dictionary is a nonsense too. Stretch (in that context) is a verb. It's both technically sloppy (and misleading) and grammatically sloppy :roll: But feel free to carry on using it

rolf_f

meanredspider wrote:

And referring to a dictionary is a nonsense too. Stretch (in that context) is a verb. It's both technically sloppy (and misleading) and grammatically sloppy :roll: But feel free to carry on using it

As I said, we aren't mechanical engineers so what you describe as technically sloppy is entirely irrelevant and incorrect. The chain is stretched (a verb - it has become stretched. The chain has stretched. It went through a process of stretching as a result of wear to the rollers. Yes - a verb!). It is longer than it previously was. How many people in the street do you think would consider describing something that has increased in length as not having become stretched? Telling the majority (and doing it smugly - less of the winks please!) that they are wrong about simple words is one reason why engineers aren't given due respect in this country.

meanredspider

Why is it being technically sloppy incorrect? As I've said, the chain might be longer, might be shorter and might be the same length - in fact, when you freewheel it's probably all three - longer on the bottom run, shorter on the top run and the same length around the rings.

Also, I bet if you asked the average bod in the street what they actually thought happened when a chain "stretched", I bet a good proportion would believe the plates had permanently stretched. That's what I hate most about the term.

As for the "engineer" thing - that's simply because we call anybody that has a vaguely technical job an "engineer". Lawyers, doctors, architects - there's generally no confusion in those terms. Equally, if we were discussing a medical or legal point, we'd generally listen to the professional. It's probably no coincidence that the countries that take their title "engineer" seriously (Germany, Italy, Japan...) still have large domestic engineering capability such as nationally-owned car industries and companies like Campag and Shimano. But, hey, in this country we can all chip into engineering topics knowing that we're right and ignoring the qualified professionals.

UndercoverElephant

As an engineer (not a mechanical one, though), I'd like to say that I don't care if a layman thinks it's stretched or worn, so long as it gets replaced before it causes problems.

desweller

UndercoverElephant wrote:

As an engineer (not a mechanical one, though), I'd like to say that I don't care if a layman thinks it's stretched or worn, so long as it gets replaced before it causes problems.

+1

If Rolf wants to be stupid that's his problem 8).

PBo

meanredspider wrote:

Why is it being technically sloppy incorrect? As I've said, the chain might be longer, might be shorter and might be the same length - in fact, when you freewheel it's probably all three - longer on the bottom run, shorter on the top run and the same length around the rings.

Also, I bet if you asked the average bod in the street what they actually thought happened when a chain "stretched", I bet a good proportion would believe the plates had permanently stretched. That's what I hate most about the term.

As for the "engineer" thing - that's simply because we call anybody that has a vaguely technical job an "engineer". Lawyers, doctors, architects - there's generally no confusion in those terms. Equally, if we were discussing a medical or legal point, we'd generally listen to the professional. It's probably no coincidence that the countries that take their title "engineer" seriously (Germany, Italy, Japan...) still have large domestic engineering capability such as nationally-owned car industries and companies like Campag and Shimano. But, hey, in this country we can all chip into engineering topics knowing that we're right and ignoring the qualified professionals.

And what do you think they think if you say the chain is worn? I bet they dont think its the bushes....I bet they don't think at all! They either say "new one please", or they think the bike shop mechanic is like a dodgy car mechanic, and think he's ripping them off. "Yeah, right, it doesn't look worn to me!". At least if the 12 inch measuring method is used, there is something visible for the layman to believe, and "stretch" will make sense to him.

Out of interest MSR, as part of some other thing I'm interested in, are you a heavy guy? How much do you weigh? Anyone else care to divulge their weight?

rolf_f

DesWeller wrote:

UndercoverElephant wrote:

As an engineer (not a mechanical one, though), I'd like to say that I don't care if a layman thinks it's stretched or worn, so long as it gets replaced before it causes problems.

+1

If Rolf wants to be stupid that's his problem 8).

I always want to be stupid but I'm not always very good at it! Trouble is, MRS is confused over the difference between an object and it's component parts. Ultimately, you could say that nothing stretches at an atomic level but that hardly helps. Stretch is a term with an engineering meaning and a term with a lay meaning in normal conversation. If MRS wants to object to stretch as term applied to chains on EngineeringRadar I'd probably be with him all the way. On here it is just pedantry.

MRS - is what upsets you actually the term applied to the chain overall or just irritation that people assume the plates stretch?

meanredspider wrote:

As for the "engineer" thing - that's simply because we call anybody that has a vaguely technical job an "engineer". Lawyers, doctors, architects - there's generally no confusion in those terms. Equally, if we were discussing a medical or legal point, we'd generally listen to the professional. It's probably no coincidence that the countries that take their title "engineer" seriously (Germany, Italy, Japan...) still have large domestic engineering capability such as nationally-owned car industries and companies like Campag and Shimano.

I'll agree that that is a big part of the problem - but refusing to talk in a language that the lay person understands hardly helps.

meanredspider wrote:

But, hey, in this country we can all chip into engineering topics knowing that we're right and ignoring the qualified professionals.

And this is exactly the superior "I know best because I have a piece of paper" attitude that causes the problems and gives engineers a bad name.

Rolf F (MSc - Engineering, Imperial College).

P.S - MRS - there is of course one reason why objecting to the term stretch has some real value but I don't think you've actually mentioned that yet! If you do I'll try to promise to shut up!

bushu

Rolf F wrote:

If MRS wants to object to stretch as term applied to chains on EngineeringRadar I'd probably be with him all the way. On here it is just pedantry.

Thats the point here no!?

I dont even think the prats near me would understand chain wear but i'm pretty sure they know the plates dont elongate unless they've just thrown it on a roaring fire thinking it may remove all prints before the law appear

meanredspider

Rolf F wrote:

And this is exactly the superior "I know best because I have a piece of paper" attitude that causes the problems and gives engineers a bad name.

Rolf F (MSc - Engineering, Imperial College).

I'd agree. You get an MSc by dint of 4 years of passing exams. You get FIMechE by dint of over 25 years of real (post graduate) engineering experience, running £30M projects and managing 60 degree-qualified scientists and engineers. The piece of paper means very little in the engineering world - the experience is everything.

I'm not confused. The chain stretches under load elastically. When it wears the wear means it can be longer or shorter or the same length as a new chain. Tyres wear, brake pads wear, rims wear, cassettes wear, jockey wheels wear, chain rings wear but chains "stretch". Bizarre.

rolf_f

meanredspider wrote:

Tyres wear, brake pads wear, rims wear, cassettes wear, jockey wheels wear, chain rings wear but chains "stretch". Bizarre.

Tyres don't stretch, brake pads don't stretch, rims don't stretch, cassettes don't stretch, jockey wheels don't stretch. Chains get longer - they stretch. Maybe a different term is unneccessary but generally, I think most people don't associate things getting longer with wear but they do associate things getting longer with stretch as per dictionary definitions. I can see why you might not like this but I can't for the life of me understand why you find it bizarre; it's human nature. Inconsistency is a great thing and is thankfully everywhere.

If you have all this experience, it doesn't show here. If you want to influence people, eg in this particular issue, telling them "I know better because I'm qualified" isn't a good way to do it. Your experience ought to tell you quite clearly that you would have been better taking a line like this -

"Whether or not you think stretch is an appropriate term is down to you but it doesn't really matter. What matters in engineering terms is understanding how that stretch develops. ie it is a combination of pin wear and roller wear rather than the actual side plates stretching. The reason that this matters is because only the pin wear alters the spacing of the chain; roller wear does not. And because most chain wear tools measure both pin and roller wear, they tend to be over cautious and result in premature rejection of still serviceable chains. Therefore, it is better to actually measure the distance between a number of pins rather than relying on the tool (though that does err on the side of caution which is probably better than leaving things too late in this instance)".

Just my opinion but I think that something like that would be a more constructive approach from an engineer rather than complaining that peoples normal use of the English language is ignorant and that you know better - I'd have thought that 25 years of postgraduate experience would have taught you that

meanredspider

Rolf F wrote:

Tyres don't stretch,

Now we are in the realms of the bizarre - of course they do.

Rolf F wrote:

Just my opinion but I think that something like that would be a more constructive approach from an engineer rather than complaining that peoples normal use of the English language is ignorant and that you know better - I'd have thought that 25 years of postgraduate experience would have taught you that

There were times in my career when I might have cared but
a. this is an internet forum
b. that was probably 10 years ago
c. I think I tried that approach a week or so ago in this thread and it got nowhere (see "a" )
d. I have to be diplomatic at work - I'm apparently quite good at it there (see "a" again )

Do I really care whether people say "stretch"? Of course not - there are far more important things to worry about. But it's sometimes fun to argue over the trivial (yup, see "a" again )

bushu

This is not a square watermelon, discuss..

meanredspider

I have no experience or qualifications as a green grocer so I couldn't possibly comment

My pedant quali and a maths A' level tells me it's nearer a cube than a square though