Chain replacement: when & why exactly?

[sootie]

I would like to start a thread about bike chains. It has been done before on this forum, but even the WOF testers still disagree about this one.
Here are some ideas:
- Never replace because it doesn't matter much!
- Replace every 10,000 kms to be on the safe side!
- Replace when it looks really dirty (one testing station argument I had!)
- Replace when the sprockets show clear "forward hooking" wear (how clear?)
- Replace when it can be lifted clear of rear sprocket (how easily?)
- Replace when reverse wheeling of bike makes chain/sprocket movement jumpy (means??)
- replace when wheel rotation gives low & high tension positions (how big?)
- Replace when chain link wear allows a stretch limit to be reached
- replace when frequent tension re-adjustment is needed. (ie more than once every 5,000 kms.)

I guess I like the stretch limit because it is definitive, and the need for frequent re-adjustment because it is indicating a rate of deterioration of chain condition to maintain a fairly standard amount of chain play.

More comments:
90% of chain wear can be avoided by keeping the chain & sprockets clean.
A high pressure water hose, relub & short run every few months and particularly after off seal use (roadbike) are the best way to avoid this????

Always replace both sprockets whenever a chain is replaced.

Love to hear some experts discuss this - what other ideas are out there?
- agreement is probably an unreasonable expectation!

[Coldrider]

just mail order a clip on shaft drive.

[bogan]

Some of that list could be separated into high torque, high lifetime, and improper maintenance effects. There's no single one to look out for, so check a few. Personally I keep an eye on sprocket condition, tight spots in the chain, and chain sag on the rear sprocket (where you can pull the back links out a significant amount). Sideways deflection is also a good indicator of chain condition, I'm surprised that isn't in your list, cos it used to me in the manuals that came with bikes...

One thing to check every now and then is the cush drive (if your bike has one obviously), play in that will jolt the chain, creating higher than normal tensile forces on the chain.

I'd be wary of pressure washing, you don't want to force crud into the important bits. Just keep the orings properly lubed to prevent any crap from working its way past, and to encourage its expulsion from the chain. I highly rate the teflon stuff as a great chain lube, non-sticky so it has minimal crud buildup.

[Gremlin]

The front sprocket always wears faster than the rear due to the smaller size (more wear).

Wear depends on riding style, power output of bike, quality of chain etc.

Come to think of it... a shaft drive is much easier

[sootie]

The front sprocket always wears faster than the rear due to the smaller size (more wear).

Wear depends on riding style, power output of bike, quality of chain etc.

Come to think of it... a shaft drive is much easier

Had not considered the front sprocket thing before - thanks

Some of that list could be separated into high torque, high lifetime, and improper maintenance effects. There's no single one to look out for, so check a few. Personally I keep an eye on sprocket condition, tight spots in the chain, and chain sag on the rear sprocket (where you can pull the back links out a significant amount). Sideways deflection is also a good indicator of chain condition, I'm surprised that isn't in your list, cos it used to me in the manuals that came with bikes...

One thing to check every now and then is the cush drive (if your bike has one obviously), play in that will jolt the chain, creating higher than normal tensile forces on the chain.

I'd be wary of pressure washing, you don't want to force crud into the important bits. Just keep the orings properly lubed to prevent any crap from working its way past, and to encourage its expulsion from the chain. I highly rate the teflon stuff as a great chain lube, non-sticky so it has minimal crud buildup.

Quite true - I had heard the sideways movement one before, but will claim a senior moment!
My impression with the water blasting (used sensibly) is that it is the most cost effective way I know to extend chain life by removing grit before much wear sets in. Removing a continuous chain from a bike for cleaning is a pretty big hassle.
Some other good points here too - thanks

[SMOKEU]

To clean the chain you should use a plastic dish scrubbing brush from a supermarket, and gently scrub the chain with kerosene to clean it. Don't use petrol or other chemicals as that can dry out the O rings and fuck the chain. Don't use a high pressure wash.

[Paul in NZ]

Replace it as often as you like...

When walking to the train I'll hear bikes going past where you can literally hear the chain rattling around over the exhaust noise... That guy is probably pushing it a little...

Or - if you have a bike like an old triumph 650 where a busted chain will smash out a piece of the crankcase and since replacement chains are cheap as chips for them, replace it often...

Its up to you - its your bike ...

[Hawkeye]

You also don't want to be on a bike if the chain decided to snap while riding......
A chain can do a lot of damage not only to crack cases but lower limbs as well

[sootie]

To clean the chain you should use a plastic dish scrubbing brush from a supermarket, and gently scrub the chain with kerosene to clean it. Don't use petrol or other chemicals as that can dry out the O rings and fuck the chain. Don't use a high pressure wash.

The brush plus kero chain clean is what has been recommended as the "standard way" since the 1950s at least.
"Bin there done that" and I am not actually impressed. ( Agree totally regarding no use of stronger solvents.)
Firstly brush cleaning involves chain removal to be even fairly effective. That is not so easy with a continuous chain as recommended for higher powered bikes (& by the Kawasaki workshop Service Manual).
Secondly, unless you use heaps of kero which has to be disposed of, you leave a lot of grit still on the chain.
Thirdly, I have never understood why brushing dirt around the O-ring edges is better than a water pressure wash at a suitable pressure. (ie just enough pressure to remove all the dirt/grease residue)

My present chain has been maintained by water blast cleaning & relub for at least 50,000kms - better than I have ever manged by other methods, and chain is only showing a bit of usage wear at this stage. (It is still within the Kawasaki specified stretch limit.)
I see no reason why dirt should be forced past O-rings by water more than by a brush, and also, water is reasonably volitile & should soon vapourise out of a chain provided it is being used & not stored.
The chain certainly appears far cleaner after a good water blast, and the cleaning in place is heaps easier.

I am aware of the issues involved in a chain break, and I agree that I do not want to go there!
I guess I am trying to follow the Air NZ maintenance idea of monitoring when the rate of deterioration starts to rapidly increase. Hence my original suggestion. Still open to ideas on this, but it seems to me it is all a bit of "guess & by god" for most bikers.

[James Deuce]

A pressure washer is the best way to ruin an O-ring, X-ring, or Z-ring chain. It will force crud past the seals and turn the grease contained into grinding paste. I think you've simply been lucky. I've seen some utter disasters caused by the method you describe. I've had chains last between 35,000 and 50,000kms, manually cleaning with kero, a rag and a the softest toothbrush you can buy.

A chain lube system of some sort like a Scotoiler is probably best.

[bogan]

Water doesn't break down the chain lube, in fact most lubes are hydrophobic. The grit is generally suspended in the lube, with not a lot else holding it on. So using kero to dissolve the lube, will require less force to then displace the grit. Disposing of the kero isn't ideal, but it doesn't take that much (less than a liter) to clean a chain, and its not that hard to do on the bike. Use a good lube means you can get away with only cleaning it once or twice per year.

[sootie]

The reality has just not matched the predictions of disaster in this case, and this is not the first chain I have used this technique on with great success. Please keep in mind that I just use enough force to slowly work the gritty grime across & off the lower edge of the chain links. I think we have some incorrect paradimes about what actually happens in practice. Lucky ????
Are you sure this is not a bit like mercury amalgam being a deadly poison which should never have been used for tooth filling? The main problem with this one is that heaps of people have walked around with a jaw full of amalgam fillings for 50 years, and have still not popped their clogs!
As a kid I was never allowed to swim for an hour after eating. Now totally rubbished. Long distance swimmers are actually advised to eat a small meal before an event.
Surely when something does not work out as predicted, it is time to re-look at the theory??
[ding-dong : round 1]

[bogan]

Surely when something does not work out as predicted, it is time to re-look at the theory??
[ding-dong : round 1]

So whats your theory? That the technique you use keeps the force low enough so as not to push crud past the o-rings? Or that high pressure washing doesn't generate enough force to push crud past the o-rings?

[Rhys]

I scrub with kero then wash it of with a finger over the end of the hose and re lube, seams to work ok for me

[sootie]

So whats your theory? That the technique you use keeps the force low enough so as not to push crud past the o-rings? Or that high pressure washing doesn't generate enough force to push crud past the o-rings?

I will go with a bit of both of those and say that I believe I have proved that it is a better & easier way.
I will add the proviso (not proven) that the chain needs to be relubed thoroughly, and then used within a day or so afterwards to make sure that any unwanted water is disposed of. (Maybe a bit does get past the O-rings.)

I have read that the main reason cam chains last far longer than drive chains on bikes is because they operate in a cleaner environment, not because of any loading difference. If you can keep a chain clean by any means, it must last longer & grit is far worse than water. (Again this is my belief, but I can not prove it.)