CrowSeph

Hello. After how many kilometers should i change my chain? (this for me sound weird since i always use a gaige to determine the wear itself and not judging by kms).
Also is i don't own a 12s wear indicator , is correct to measure with a gauge and replace when the measure hit +.5?
for example a new chain will measure 134.4mm (6 chainmail i belive), after the chain it's worn out must measure 134,9. is it correct?

ps. i have an ultegra di2 12s

alcjphil

The pitch of your 12 speed chain is no different than any 11 speed, 10 speed, 9 speed, etc chain. It is very simple to measure chain wear using a ruler. Don't overthink things

Iride01 

On a new chain with no wear, the pin would be at 12 inches or 304.8mm. 306.3 mm would be the same as the 12-1/16 inches that most consider worn out . Make sure your origin and point you measure to are either the center of the pin or the same side of the pin.

choddo

what wear indicator do you own? That should work.

Iride01 

I read something a while back that some 12 speed chains have different roller diameters than 11 speed or less chains. That'd make a lot of chain checkers useless for them.

I haven't seen this discussed much, so I could be wrong.

alcjphil

What brand of chain? I have heard the same thing about SRAM 12 speed chains that may not work with anything else, effectively locking the consumer into using their stuff

Iride01 

alcjphil we must have seen the same thing. It was about SRAM's chains. There are various blogs and such about it if you google 12 speed chain roller size

FBinNY 

There's no formula for chain life. Light riders in the plains will get long life, while heavier riders in hill country will eat chains. Other factors like gear selection (smaller spockets increase chain wear), chain lube, and riding style all make a difference.

As for wear indicators; since the chain's have the same 1/2" pitch, the same rules for measuring with a ruler would apply, as would the when to replace guidelines.

Note. I said "guidelines" because that's all that they are. For my part, I use a sliding scale, being conservative with replacing the 1st chain on a new cassette, and moving to allowing more wear as the cassette is aging.

IMO folks tend to overly obsess over this, and don't allow themselves realistic fudge room. By analogy, do you stop and seek out a service station for an oil change the minute your odometer ticks off 2,500 miles, or just make a note to change oil at your next convenience?

choddo

Well that would be deeply unhelpful.

CrowSeph

The classic with two measure , 0.75/1

choddo

So then I guess as long as it’s not one of those SRAM chains as above which seem to have bigger rollers, you should be able to rely on that.

Maybe it would be ok anyway, the delta would be about 0.15mm on the AXS one according to google.

1% stretch would be 1.5mm over about 6 inches are the tools that long? 12 links? Close enough I reckon

.75% would be 1.125mm
add on the 0.15mm of the bigger rollers gives approx 0.85% at 6 inches
so I reckon you could treat the .75% side (net .85% real stretch on one of those chains) as a useful marker.

grumpus

SRAM Eagle 12 speed MTB transmission is proprietary and not compatible with "standard" powertrain parts*. It was discussed here recently.


* The great thing about standards, of course, is that there are so many to choose from.