Are chain checkers accurate?

Signal_ rabbit

I read somewhere that they aren't as they don't take into account roller wear. When its inserted into the chain it pushes against the rollers each end thus adding this measurement.

My chain is worn according to my park tool, but when measured with a rule it is within 0.5mm of the 12inch mark.

So hence my question.?

papac

I have no experience of chain checkers but I would be inclined to believe an accurate rule. In your shoes I would be doubting the chainchecker.

Deisetrek

papac wrote: »

I have no experience of chain checkers but I would be inclined to believe an accurate rule. In your shoes I would be doubting the chainchecker.

As with papac , I'd be inclined to trust the 12 inch rule (a steel rule not a tape) . I have never used a chainchecker . Can you see daylight between the chain and teeth if you lift it off the biggest front chainring ? If so get rid of it , a new 8 speed chain ( SRAM PC850) is about 12 euro on CRC. I'd change that Sram cassette as well (PG850) , they often wear as a pair , and they're cheap . I change my chain/ cassette about twice a year or every 2000 miles or so . My bike usually tells me when I'm due a change with jumpy chain engagement on the small sprockets at the rear .

IM0

like all guides they are a good...guide. I've used them for years and they have been good. Id much rather something underestimated on a part that costs 20 quid, and saves the need to replace the cassette as well.

go with chain checkers and replace the cassette after every 3rd chain..if done right. its worked fine for me for years, Im a spinner though not a masher.

Deisetrek

me@ucd wrote: »

like all guides they are a good...guide. I've used them for years and they have been good. Id much rather something underestimated on a part that costs 20 quid, and saves the need to replace the cassette as well.

go with chain checkers and replace the cassette after every 3rd chain..if done right. its worked fine for me for years, Im a spinner though not a masher.

Agreed it's not ALWAYS necessary to replace as a pair , I've a Shimano 105 groupset on my other bike and after 7000 miles or so the chain is only now starting to show signs of wear . You get what you pay for I suppose , the Sram PG850 on my Trek 1000 wears quickly but is cheap to replace .

Single Malt

Signal_ rabbit wrote: »

I read somewhere that they aren't as they don't take into account roller wear. When its inserted into the chain it pushes against the rollers each end thus adding this measurement.

My chain is worn according to my park tool, but when measured with a rule it is within 0.5mm of the 12inch mark.

So hence my question.?

Chain checkers do account for that. Chains do not physically stretch much. Instead the pins, bushes and rollers wear. This changes the effective pitch of the chain, cos the working parts don't fit the way they are supposed to. You cannot measure this, unless you insert a guage into the chain that measures the effective pitch by pushing the working parts apart.

The pin to pin distance is not accurate, as that takes no account for the state of wear on the roller, and only measures the strech of the plates, which is irrelevant in relation to the pin, bush and roller wear (which happens faster that the links stretch)

tomasrojo

I usually change the chain after two or three thousand kilometres, but since I now have mudflaps on both my bikes, I'm getting much less schmutz on the chain, so the chain seems to be lasting much longer. But I'm using the tape-measure method, so perhaps I'm not measuring it accurately enough.

papac

Single Malt wrote: »

Chain checkers do account for that. Chains do not physically stretch much. Instead the pins, bushes and rollers wear. This changes the effective pitch of the chain, cos the working parts don't fit the way they are supposed to. You cannot measure this, unless you insert a guage into the chain that measures the effective pitch by pushing the working parts apart.

The pin to pin distance is not accurate, as that takes no account for the state of wear on the roller, and only measures the strech of the plates, which is irrelevant in relation to the pin, bush and roller wear (which happens faster that the links stretch)

Makes sense now that I think about it.
The ruler has served me ok for years though. I am quite anal about cleaning and lubricating chain though so I may be getting a better representation of overall wear from pin distance.

Single Malt

papac wrote: »

Makes sense now that I think about it.
The ruler has served me ok for years though. I am quite anal about cleaning and lubricating chain though so I may be getting a better representation of overall wear from pin distance.

No, not by much, because the pins wear regardless of how anal you are. Ever notice the two grooves worn into the pin when removing an old worn chain? That makes up the bulk of chain wear, and will always happen faster than the physical stretch of the metal, and that is the main culprit for the change in effective pitch

tomasrojo

I don't think the metal stretches at all, does it?

http://sheldonbrown.com/chains.html#stretch
I thought this article was accurate, but maybe it's not quite. It does claim that using a tape measure gives you a direct measure of wear to the chain. I've always assumed this claim is justified by the fact that the hinge pins and sleeves wear out with use, which results in a greater distance between the links (which is misleadingly called chain stretch).

This article suggets that chain checkers can give misleading indications of wear.
http://pardo.net/bike/pic/fail-004/000.html

Commercial tools are conservative and never report a chain as good when it is actually worn. They may, however, report a good chain as worn, leading to increased chain costs.

This seems ok to me, in some ways, since it's better to replace a chain somewhat prematurely than somewhat late.

This is far from any area in which I have expertise, so I'm not disagreeing with anyone on either side. I'll continue to use the ruler method because I know how to do it and it seems to work well enough for me.

papac

Curse you all. I can't stop thinking about this now.Don't you know I have Bicycle related OCD.?

Signal_ rabbit

I winder if the choice of lube has any bearing on chain life? I use a wax lube and find that chain life is very short compared to others in the club who swear by Finish line wet and dry lube.

papac

Signal_ rabbit wrote: »

I winder if the choice of lube has any bearing on chain life? I use a wax lube and find that chain life is very short compared to others in the club who swear by Finish line wet and dry lube.

Old chestnut and everyone has their own preference.
I think that how well/often you clean and degrease your chain is more important than the type of lube you use.
I also think that cheap engine oil (SAE30 from motor factors). is just as good as the proprietary (expensive) chain lubes.

tomasrojo

papac wrote: »

Old chestnut and everyone has their own preference.
I think that how well/often you clean and degrease your chain is more important than the type of lube you use.
I also think that cheap engine oil (SAE30 from motor factors). is just as good as the proprietary (expensive) chain lubes.

Yes, I think that's pretty much it (thought the lube can make a difference if it washes out too easily, or holds on to too much grit).


Jobst Brandt points out:

Chain wear depends almost entirely on cleanliness and lubrication

For example, motorcycle primary chains, operated under oil in clean conditions, last as much as 100,000 miles while exposed rear chains must be replaced often.

http://www.sheldonbrown.com/brandt/chain-care.html