How to use a chain wear tool

[derrick]

Quoting the IGM:

So @derrick you haven't made any effort to support your contrary assertion that: "A new chain does shift better than a worn one".

I do not need to, I fitted a new chain last week, My front derailleur now shifts cleanly, That's enough for me.

 

[Citius]

"it works for me" - the internet's greatest get-out clause....

 

[Smokin Joe]

Never measured a chain in my life.

1500 mile = bin and replace. Keeps things simple and hasn't driven me to bankruptcy.

 

[bpsmith]

Actually replaced mine at 1,500 miles this year too. At less than £20 a pop I am with @Smokin Joe. When I get to my third chain, I will see how the cassette and chain rings look and might ride for Neil they wear out, just to see what mileage is like. That's assuming they are showing signs of wear mind you.

 

[EasyPeez]

I have never experienced worsening shift performance from a worn chain

Further, a worn chain does not affect shifting at all. A good chain or a worn chain will shift equally good or bad on the same setup.

I don't have the scientific knowledge that other contributors to this thread clearly have, but I am interested to know what was going on with my bike (i.e why my chain started slipping) if the above assertions are true.

My (admittedly very limited) experience teaches me that a chain will start to slip as it becomes worn, and this problem will intensify the more worn the chain becomes. I have changed only one chain since starting road cycling last year. This was my experience -

I indexed my gears after the first couple of hundred miles of riding and then never needed to touch them again. I measured my chain wear periodically and found that my measuring tool indicated .75 wear after approx 2,100 miles of riding. Being even more naive then than I am now, I continued to ride my chain as it seemed to be performing as well as ever. Within another 100 miles, the chain had slipped 2 or 3 times on the cassette, something that had never happened previously. I rode the bike on 3 or 4 more long-ish rides after this whilst waiting for a new chain to arrive in the post, and on each of these rides my chain slipped regularly on each ride, to the point where I could not cycle uphill with any confidence. By this time I had done approx 2,400 miles in total and the chain was showing 1% wear.

I fitted the new chain, indexed the gears and, to date, have not experienced the chain slipping again.

I realise now that I was silly to go on riding the previous chain to the point that I did. But what caused my chain to start slipping if not the chain wearing?

Thanks.

 

[Ajax Bay]

what caused my chain to start slipping if not the chain wearing?

The chain wearing beyond 0.75% -> 1% probably caused your chain to slip. The discussion above was over whether a worn chain shifted less well than a new one, not about whether a worn chain slips (which it does). Indexing 'decides' = leads the chain to the desired sprocket, not under much tension, and then to the adjacent one, and whether a chain is worn or not makes little difference: at least that is @Yellow Saddle 's thesis. I've seen no evidence to disagree and @derrick just 'knows' that a new chain works for him.

You may wish to consider replacing the cassette as you may have done some damage to it by letting the chain stretch beyond 1%.

 

[Citius]

I fitted the new chain, indexed the gears and, to date, have not experienced the chain slipping again.

I realise now that I was silly to go on riding the previous chain to the point that I did. But what caused my chain to start slipping if not the chain wearing?

See the bit in bold...

 

[EasyPeez]

The discussion above was over whether a worn chain shifted less well than a new one, not about whether a worn chain slips (which it does). Indexing 'decides' = leads the chain to the desired sprocket, not under much tension, and then to the adjacent one, and whether a chain is worn or not makes little difference

Ah, fair enough. To me the notion of selecting a new gear and the chain moving across but then not being able to retain that gear equates to poor shifting, but I guess if we're breaking the whole process down to it's constituent parts and in this case using the term shifting to refer only to the movement (and efficiency thereof) of the chain between sprockets then I guess I can't argue with that. Thanks for clarifying.

You may wish to consider replacing the cassette as you may have done some damage to it by letting the chain stretch beyond 1%

Yeah, I've since changed to a smaller cassette anyway, but thanks for the tip.

See the bit in bold...

If you're suggesting the indexing of the gears was the key action in all this, then surely it should follow that I could have indexed the gears before changing chains and carried on as normal. Doesn't seem likely to yield positive results in the long term...?

 

[Yellow Saddle]

I don't have the scientific knowledge that other contributors to this thread clearly have, but I am interested to know what was going on with my bike (i.e why my chain started slipping) if the above assertions are true.

My (admittedly very limited) experience teaches me that a chain will start to slip as it becomes worn, and this problem will intensify the more worn the chain becomes. I have changed only one chain since starting road cycling last year. This was my experience -

Your inexperience with chains deceived you. As a chain wears, it starts to elongate and the pitch (distance from roller to roller) starts to increase. This places the chain out of sync with the sprocket and to make a long story short, the sprocket then wears with the chain. On a multi-sprocket cassette, the sprockets you favour wear more than the others. When you then fit a new chain, the new chain's proper pitch is out of sync with the worn sprockets and it skates (term for sliding over the top of the teeth without engaging) on those sprockets under high pressure like when pedaling hard up a hill. Soft pedaling doesn't produce skate. Skating happens even with perfectly indexed gears since it has nothing to do with not properly engaging laterally, but sliding over the top. If a derailer is not indexed properly, it causes another type of "slip" we call skipping. It literally skips between gears. Your description does not tell us which type of slipping happened.


I indexed my gears after the first couple of hundred miles of riding and then never needed to touch them again. I measured my chain wear periodically and found that my measuring tool indicated .75 wear after approx 2,100 miles of riding. Being even more naive then than I am now, I continued to ride my chain as it seemed to be performing as well as ever. Within another 100 miles, the chain had slipped 2 or 3 times on the cassette, something that had never happened previously. I rode the bike on 3 or 4 more long-ish rides after this whilst waiting for a new chain to arrive in the post, and on each of these rides my chain slipped regularly on each ride, to the point where I could not cycle uphill with any confidence. By this time I had done approx 2,400 miles in total and the chain was showing 1% wear.[/QUOTE]
Again, I cannot make a diagnosis because I am not sure what type of slipping happened and if you are not attuned to such things, you'll not be able to ID it retrospectively. I suspect it was a derailer/cable malfunction for whatever reason. Miss-shifts happen.

I fitted the new chain, indexed the gears and, to date, have not experienced the chain slipping again.

I realise now that I was silly to go on riding the previous chain to the point that I did. But what caused my chain to start slipping if not the chain wearing?

Thanks.

The fact that your chain tool said the chain was worn to 1% and that you managed to fit a new chain and not a new cassette, and then went on to ride without problems, tells me that the chain tool and/or your measuring technique is flawed. A chain that has elongated by 1% of its overall length (note that I don't say it has worn by 1% or somesuch) has already damaged one or more sprockets to the point where a new chain will not work with it. It will skate in the most worn sprockets when pedaling hard. You thus fitted a new chain to a unworn sprocket and therefore the tool is optimistic and designed to tell chains. Once a riders learns to distinguish between chain skate, chain skip and chain slip, remote diagnosing problems become easy. Otherwise it remains a guess.

 

[EasyPeez]

As a chain wears, it starts to elongate and the pitch (distance from roller to roller) starts to increase. This places the chain out of sync with the sprocket and to make a long story short, the sprocket then wears with the chain. On a multi-sprocket cassette, the sprockets you favour wear more than the others. When you then fit a new chain, the new chain's proper pitch is out of sync with the worn sprockets and it skates (term for sliding over the top of the teeth without engaging) on those sprockets under high pressure like when pedaling hard up a hill. Soft pedaling doesn't produce skate. Skating happens even with perfectly indexed gears since it has nothing to do with not properly engaging laterally, but sliding over the top. If a derailer is not indexed properly, it causes another type of "slip" we call skipping. It literally skips between gears.

Thanks, that's an excellent explanation and makes the processes at work very clear.

Your description does not tell us which type of slipping happened

Based on your definitions, I believe it was skipping. The chain would slip from one sprocket on the cassette to the next one, or sometimes two, down (i.e into higher gear - no fun when coming as a surprise up a steep incline!). If I've understood your explanations correctly this should not relate then to chain wear. Seems odd that the problem only began as the chain passed .75% wear and became more prevalent the more the chain became worn. Coincidence, perhaps.

The fact that your chain tool said the chain was worn to 1% and that you managed to fit a new chain and not a new cassette, and then went on to ride without problems, tells me that the chain tool and/or your measuring technique is flawed

I did fit a new cassette along with the new chain, sorry if this was unclear from the original post. There was neither skipping nor skating as soon as the new components were installed, and just the slightest of adjustments to the indexing was required to get the whole thing running perfectly.

 

[Yellow Saddle]

Based on your definitions, I believe it was skipping. The chain would slip from one sprocket on the cassette to the next one, or sometimes two, down (i.e into higher gear - no fun when coming as a surprise up a steep incline!). If I've understood your explanations correctly this should not relate then to chain wear. Seems odd that the problem only began as the chain passed .75% wear and became more prevalent the more the chain became worn. Coincidence, perhaps.

Not really, as the chain gets used more, the gear cable was also used more and started to get dirty, sticky or worn. Gear cables don't stretch but the inner cable wears a shortcut through the soft plastic housing on the inside radii of bends in the cable. This then makes the inner relatively longer than the outer, putting indexing out.

I did fit a new cassette along with the new chain, sorry if this was unclear from the original post. There was neither skipping nor skating as soon as the new components were installed, and just the slightest of adjustments to the indexing was required to get the whole thing running perfectly.

You will not remember from the adjustment, but I'm pretty sure that you had to screw the barrel adjuster out a tad. That would have compensated for the inner's new length relative to the worn outer and fixed the indexing and resultant skipping instantly.

 

[EasyPeez]

Gear cables don't stretch but the inner cable wears a shortcut through the soft plastic housing on the inside radii of bends in the cable. This then makes the inner relatively longer than the outer, putting indexing out

Yes, but that happens within the first couple of hundred miles doesn't it? And then things settle. Hence me indexing the gears quite early into ownership and then never needing to touch them again until changing chains. Surely the cable housing doesn't stop wearing for nearly 2,000 miles of gear changes, and then start wearing again all of a sudden? Besides which, when the wearing took place it resulted in the chain 'agitating' in certain sprockets, and sometimes missing changes up the cassette (i.e into a lower gear) but never created enough of a difference in indexing to cause to the chain to drop down 2 sprockets.

Btw - I'm not having a pop at you here. I appreciate you taking the time to share your knowledge. Just trying to understand the workings of my bike better

 

[Yellow Saddle]

Yes, but that happens within the first couple of hundred miles doesn't it? And then things settle. Hence me indexing the gears quite early into ownership and then never needing to touch them again until changing chains. Surely the cable housing doesn't stop wearing for nearly 2,000 miles of gear changes, and then start wearing again all of a sudden? Besides which, when the wearing took place it resulted in the chain 'agitating' in certain sprockets, and sometimes missing changes up the cassette (i.e into a lower gear) but never created enough of a difference in indexing to cause to the chain to drop down 2 sprockets.

Btw - I'm not having a pop at you here. I appreciate you taking the time to share your knowledge. Just trying to understand the workings of my bike better

Relax, no pop perceived. I'm happy to explain, I just hope I understand the questions properly.

Gear cable wear is gradual. It is a fretting (filing) action of the inner cable that constantly moves up and down against the inner edge of the outer cable. With each gear change, it moves a few mills and the process is pretty linear. Usually if you have to fiddle with gears directly after a cable replacement it is because the outer cable wasn't properly settled in the ferrules or, the plastic ferrule could not handle a sharp bend and settled in a new curved position. Properly installed cables see to it that indexing remains in tune for the life of the cable or until the derailer is bumped. The way you describe the missed changes indicates a cable problem, be it in the cable, at the bottom bracket where it slides without a housing or anywhere else along the length of the cable. But, without the bike in front of me, it is all speculation.