Changing the Chain

[Gareth Bowen]

Morning all.
Went to buy new chain for my levo yesterday and was told by tredz that mine was 100 percent used (never had problems though).! Back cassette looks fine to me but they reckon that chain would jump under pressure . Anyone experienced this then
Gar B

 

[GrahamPaul]

What elongation does the chain checker show? My mate is a tightwad when it comes to changing chains, has a 1% elongation and claims that, when the chain snapped and he had to take out a couple of damaged links, that the gear change is back to near perfect ?‍

 

[steve_sordy]

Chains and gears wear out together. But the worse the chain is, the faster the gears wear. That is why the general experience is to change the chain at 0.75% length extension. That way, you should get three chains per cassette. If you leave the chain running until it is past 1% then almost by definition, the gears will be worn out, all of them front and rear.

I used the word "general" above because there are always exceptions that riders will report. But you cannot compare someone who commutes on dry tarmac in California with someone who rides in a muddy, wet and gritty UK winter (me). I have also discovered that 12-speed chains last a lot longer than any other speed chain I have used. SRAM say that the chains are made in a different way and to a different design. They must be.

Because chains are cheap and gears are not, many follow the advice above. Some go to the lengths of changing the first chain at 0.5%, then the 2nd and the 3rd, then go back to the 1st and so forth.This has the effect of wearing out all the chains and gears together. The key factor is that the 4th chain (the 1st one used for the 2nd time) is already partially worn and is not startling different to the wear on the gears and as a consequence they do not react badly to each other. Those that do this report back favourably. But when the end comes, everything is totally shagged. What is happening to your shifting while all this is going on is not reported.

 

[steve_sordy]

What elongation does the chain checker show? My mate is a tightwad when it comes to changing chains, has a 1% elongation and claims that, when the chain snapped and he had to take out a couple of damaged links, that the gear change is back to near perfect ?‍

At 1% extension, a 116 link chain is 1.16 links longer than new. Removing two links restores the chain to a bit shorter (ie tighter) than its previous length when new. Therefore when the mech arm is fully forward it will be a bit more forward then when the chain was new. I'm guessing that it will put a bit more tension on the lower strand and help to reduce chainsuck.

Or it may have been that the chain had been damaged for some time, messing with the shifting, before it finally snapped. Removing the damaged links removed the problem.

 

[Gareth Bowen]

What elongation does the chain checker show? My mate is a tightwad when it comes to changing chains, has a 1% elongation and claims that, when the chain snapped and he had to take out a couple of damaged links, that the gear change is back to near perfect ?‍

Thanks for that ?

 

[Gareth Bowen]

Chains and gears wear out together. But the worse the chain is, the faster the gears wear. That is why the general experience is to change the chain at 0.75% length extension. That way, you should get three chains per cassette. If you leave the chain running until it is past 1% then almost by definition, the gears will be worn out, all of them front and rear.

I used the word "general" above because there are always exceptions that riders will report. But you cannot compare someone who commutes on dry tarmac in California with someone who rides in a muddy, wet and gritty UK winter (me). I have also discovered that 12-speed chains last a lot longer than any other speed chain I have used. SRAM say that the chains are made in a different way and to a different design. They must be.

Because chains are cheap and gears are not, many follow the advice above. Some go to the lengths of changing the first chain at 0.5%, then the 2nd and the 3rd, then go back to the 1st and so forth.This has the effect of wearing out all the chains and gears together. The key factor is that the 4th chain (the 1st one used for the 2nd time) is already partially worn and is not startling different to the wear on the gears and as a consequence they do not react badly to each other. Those that do this report back favourably. But when the end comes, everything is totally shagged. What is happening to your shifting while all this is going on is not reported.

Shifting is perfect .
Shop says chain is at 1%

 

[steve_sordy]

Shifting is perfect .
Shop says chain is at 1%

Then keep the chain on and see how you go.
One explanation is that the shop has measured the chain poorly.

A very accurate way to measure chain extension (ie wear) and requires no special tools is to remove the chain and lay it on its side on a flat surface. Pull the chain taut and straight and measure 100 links with a steel tape measure. A new chain will measure 50", one with 1% wear will measure 50.5". Measuring to an accuracy of 1/16 of an inch (0.125%) is easy with a steel tape measure, but you might need some help ensuring that the idiot end stays over the centre of a pin. 0.75% will measure 50-3/8" If you can do fractions and %ages then you can see how easy it is to establish the exact % wear of the old chain.

The advantage of this method is that by measuring over such a long distance it averages out any inconsistencies along the chain (they do vary). The typical go/nogo gauge is only accurate when new and only tells you it's over this and under that.

 

[Gareth Bowen]

Then keep the chain on and see how you go.
One explanation is that the shop has measured the chain poorly.

A very accurate way to measure chain extension (ie wear) and requires no special tools is to remove the chain and lay it on its side on a flat surface. Pull the chain taut and straight and measure 100 links with a steel tape measure. A new chain will measure 50", one with 1% wear will measure 50.5". Measuring to an accuracy of 1/16 of an inch (0.125%) is easy with a steel tape measure, but you might need some help ensuring that the idiot end stays over the centre of a pin. 0.75% will measure 50-3/8" If you can do fractions and %ages then you can see how easy it is to establish the exact % wear of the old chain.

The advantage of this method is that by measuring over such a long distance it averages out any inconsistencies along the chain (they do vary). The typical go/nogo gauge is only accurate when new and only tells you it's over this and under that.

Excellent info .Much appreciated
Gar B

 

[Gareth Bowen]

Thanks to both for replying
Gar B

 

[HikerDave]

Then keep the chain on and see how you go.
One explanation is that the shop has measured the chain poorly.

A very accurate way to measure chain extension (ie wear) and requires no special tools is to remove the chain and lay it on its side on a flat surface. Pull the chain taut and straight and measure 100 links with a steel tape measure. A new chain will measure 50", one with 1% wear will measure 50.5". Measuring to an accuracy of 1/16 of an inch (0.125%) is easy with a steel tape measure, but you might need some help ensuring that the idiot end stays over the centre of a pin. 0.75% will measure 50-3/8" If you can do fractions and %ages then you can see how easy it is to establish the exact % wear of the old chain.

The advantage of this method is that by measuring over such a long distance it averages out any inconsistencies along the chain (they do vary). The typical go/nogo gauge is only accurate when new and only tells you it's over this and under that.

Yeah 1% is probably too far gone for a new chain but still OK to ride. A new chain would just skip under load and be a waste of money.

 

[Gareth Bowen]

Yeah 1% is probably too far gone for a new chain but still OK to ride. A new chain would just skip under load and be a waste of money.

Thanks