Chain Wear Indicator - precision?

dinyull

Yesterday I bought this chain wear indicator:
http://www.chainreactioncycles.com/cyclo-chain-wear-indicator/rp-prod42815?utm_source=Google&utm_medium=Shopping&utm_name=UnitedKingdom&gs=1&gclid=CJv45bnklcMCFSrjwgod8pQAQA&gclsrc=aw.ds

You might have to bear with me here trying to best explain myself.

When I sit the tool on the chain, there is play in the 'bedding' - ie, the tool doesn't sit tight on the chain pivot meaning you can move the tool left and right. This changes readings, as if I push the tool hard left then the chain is worn 1.00%, if I push the tool hard right then the chain hasn't worn 0.75%.

Is this just me being a bit of a pleb or should I expect the tool to sit tightly on the chain pivot to give correct readings?

jermas

The tool should gently force the chain apart to give a reading. This should help http://weldtite.co.uk/uploads/products/leaflets/07902/07902%20chain%20wear%20ind%20(sml).pdf

dinyull

I get that.

Sorry, I've struggled to explain my problem:

Going from the linked pdf, the 'bridged end' that sits on the chain roller is bigger than the chain roller meaning the tool can be moved (only slightly) left and right fairly easily.

Ouija

Bad design. Get the ParkTools one that hooks round the back of the roller instead of sitting on top of it and allowing forward/backward play.

Having said that, i'd be inclined to believe the reading of the Weldtite when it's pushed to the left.

keef66

Dinyull wrote:

I get that.

Sorry, I've struggled to explain my problem:

Going from the linked pdf, the 'bridged end' that sits on the chain roller is bigger than the chain roller meaning the tool can be moved (only slightly) left and right fairly easily.

If you can fit the pointy end right into the chain it means it's worn by at least that amount.

And if you've exceeded 1% you'll likely need a new cassette as well as a chain.

I have the Park Tool equivalent and it too pushes the rollers apart when inserting it, but if the chain's not worn it won't drop in regardless of how hard you push.

dinyull

The problem isn't that it's pushing the rollers apart, its the tool itself not sitting tightly on the rollers and allowing a bit of play. Seems like a design flaw to me, seeing as it's supposed to be a precision tool.

Chain and cassette only have 1500 miles on them so knew the chain would be coming up for renewal, but the cassette should be fine.

Anyway, I've ordered a new chain and Park Tools chain wear tool. Cheers

keef66

1500 miles is roughly what I've been getting from 10 speed Shimano chains; 105 cassette has outlasted 4 chains but I'm replacing both next time.

rolf_f

Dinyull wrote:

The problem isn't that it's pushing the rollers apart, its the tool itself not sitting tightly on the rollers and allowing a bit of play. Seems like a design flaw to me, seeing as it's supposed to be a precision tool.

Chain and cassette only have 1500 miles on them so knew the chain would be coming up for renewal, but the cassette should be fine.
Anyway, I've ordered a new chain and Park Tools chain wear tool. Cheers

It's not a precision tool and neither is the Park one. They are equally crap in that they measure both roller and pin wear. And roller wear doesn't matter.

The rollers are worn by contact between the outside of the roller and the cassette and chainrings. The effective diameter of the outside of the roller changes as it wears but the pitch does not so roller wear doesn't cause slippage. On the other hand, the pins wear by contact with the inner face of the rollers. This does change the pitch because the roller can move back and forth over the pin.

Any chain wear tool that pushes the rollers apart therefore measures both the pin and roller wear which means you might be condemning a chain early. The only tools that are accurate are those where the same side of the roller is used - eg Shimano CN40 or CN41

I use the Park one but just as a guide (only because I didn't know any better when I ordered it!). Once the chain is over 0.75 I start using a ruler which is perhaps the best way to do it. Each pair of links should be one inch long.

This explains things nicely - http://pardo.net/bike/pic/fail-004/000.html

cycleclinic

They are a guide but a good one. If it very close to the 0.75% wear mark I normally change the chain ßlikewise if it over I change the chain. You can use your judgement and if your cassettes are cheap they maybe no cost benefit to early chain changes.

veryslowtwitch

Hi, I found the simple Park tool not to be "crap". If it measures 0.75-1% wear then I remove the chain which is invariably about one link longer than the new one. Given that a chain is about 110 links or so then this is pretty close to 1%.

I have found that the pin distance has always increased significantly if this little tool shows wear. Every time. Yes it might push the rollers apart but who cares?, it will show chain stretch pretty accurately.

I would be very interested to know if it shows 1% wear in a chain without significant stretch. If so then I will get the Shimano tool but it is hard to see how the rollers could wear significantly while leaving the pins intact.

I suspect that Park know about these things.

Regards

Alan

keef66

Having read and digested that article several times in the past, it occurs to me that the simple tools are only adding 2 x the wear of a single roller to the overall measurement of chain elongation. So as far as I'm concerned, it's accurate enough given how quick and simple they are to use.

I don't do an intergalactic mileage like some forumites, so I like an excuse to treat the bike to a shiny new chain. If I was commuting 30,000 miles a year I might think differently.

rolf_f

veryslowtwitch wrote:

Hi, I found the simple Park tool not to be "crap". If it measures 0.75-1% wear then I remove the chain which is invariably about one link longer than the new one. Given that a chain is about 110 links or so then this is pretty close to 1%. I have found that the pin distance has always increased significantly if this little tool shows wear. Every time. Yes it might push the rollers apart but who cares?, it will show chain stretch pretty accurately. I would be very interested to know if it shows 1% wear in a chain without significant stretch. If so then I will get the Shimano tool but it is hard to see how the rollers could wear significantly while leaving the pins intact. I suspect that Park know about these things. Regards Alan

As a precision instrument it is undoubtedly crap - but, like I said, even I find it useful. Park do know about these things. They are a private company whose business it is to make money. They probably know that most people don't understand chain wear (eg even the BR article about service items we forget indicates they know little about either the process or the tools or what is available) and that making a tool like Shimano do needs almost twice as much metal and probably won't sell for twice the money. Ultimately, Park make some decently adequate tools and some absolute junk and they don't seem fussed about the inconsistency!

As for pin vs roller wear. How about looking at it this way.

1) As per the link I posted, it is clear that only pin/inner face of roller wear matters.
2) For the pin to wear, contaminants (ie fine metal dust) must get in between the roller and the pin.
3) Many people on this forum swear that the only cleaning their chains need involves running a rag soaked in something over the chain.
4) Realistically, there is no way that wiping the outside of the chain with anything is going to get rid of all the fine particles between the roller and the pin.
5) Therefore, people using this cleaning regime will have the pins wearing disproportionately faster than someone who uses a cleaning method that does get in between the pins and rollers (I take my chains off and cook them in degreaser - when they come out they are as smooth as a new chain. Nothing else I've tried - eg chain cleaning devices can match this though these are a good quicky method).

My current chain is less than 1/16th inch over a 1 foot length (so fine according to Sheldon) yet is 1% on the Park Tool. The Park tool would have had me bin the chain 100s of miles ago.

keef66 wrote:

Having read and digested that article several times in the past, it occurs to me that the simple tools are only adding 2 x the wear of a single roller to the overall measurement of chain elongation.

But the wear that counts is only a tiny amount off the pins. 2x the wear of a single roller might result in you halving the life of the chain!

Best way to do it is to use the Park tool to 0.75 and then use a ruler afterwards. The Park tool can't underestimate wear so it is a safe tool. Just a very imprecise one!

jermas

The simplest most accurate way to determine stretch is to hang the full length of the chain from a nail next to a new one. Measuring just 12" with a ruler can result in inaccuracies trying to judge 1/16" . Chain checkers tally quite well,even though their design is slightly flawed ( the shimano one is perfect apart from the price).