mountainwalker

I just want to be able to know when my chains are at a point when they should be replaced, before they start to damage more expensive parts like cogs and cassettes. I'd guess that would be at about 75% wear - or should that be less?

Don't mind using metal machine ruler + tool, just want to have a simple reliable method.

Which method and tool/s would you recommend?

doctor j

I've had good luck with a Park Tool CC-3 tool. It has marks for 0.75% and 1.0% chain wear.

Some folks don't like the chain-check tools and will say that only a metal scale is accurate. They will say they've seen the checkers show that a brand new chain is greater than 1% worn. Then we will hear that chains don't actually stretch and that it's something else. You've unknowingly opened a can of worms much like threads on helmets, chain lube, dogs etc.

Anyway, I've had good luck with the CC-3. YMMV. Measurements are quick and easy.

Retro Grouch 

You're only measuring about 1/2 a percent so that requires a pretty precise measurement.

The thing that I don't like about chain checkers is they only measure a small amount of chain so a very tiny measurement error can be a big deal. If you choose to use one, I'd recommend calibrating it against a brand new chain. Since you know that's zero wear, if it reads anything but zero be sure to take that into account as you use it.

The trick with using a steel ruler is where to start your measurement. I used to try measuring center to center of a rivet but that involves too much guesswork. Now I measure from the start of one rivet to the start of another.

10 Wheels

I clean the chain then measure by hanging it up.

jyl

A ruler works fine, if you're not in a hurry and have good eyesight.

LesterOfPuppets

Steel ruler for me. Measure from edge of a pin on the 13" mark to the edge of the pin past the 1" mark.

Westcott® 15" Stainless Steel Office Ruler with Non Slip Cork Base | Make More Happen at Staples®

I also use Park SBC1, but I can only really use it in broad daylight. Lately I've been thinking I should sand all the blue off the surface, leaving blue in the demarcations...

FBinNY 

On the bike a 12" ruler is just about the most reliable because it measures the longest sample. It doesn't have to be precise since it's an eyeball measurement, but it does have to have good ends. Otherwise measure only 11-1/2" from the 1/4" mark to the 11-3/4" mark.

Measure the lower chord, while pulling the RD pulley back slightly to pull up all slack and lift the chain into a straight line.

In a pinch I simply use an 8.5x11" sheet of paper which is always cut precisely, and eyeball the stretch using the pin diameter as a reference.


Off the bike, hang the chain and measure at 4'

No matter how you measure, the SAFE guideline is 1/2%, or 1/16" over 12", or 1/4" over 4'. There's fudge room to double that but at 1% stretch you might as well leave the chain on because a new one is likely to skip.

fietsbob

FWIW KMC makes a Digital chain wear measurement Shop tool,

Reynolds 

This has been discussed here a number of times. I remember reading that measurement tools are fancier but not as accurate as a ruler, because they show the distance between rollers and not between pins, which is what really matters.

RoadTire 

Finally. A chance to post my very own pocket chain wear chart. Late night obsessive .... stuff. I was stuck with a 12 in ruler and really cannot measure 12 1/16 inch easily. So this turns out to pretty easy an plenty accurate enough.




Addendum: accurate enough is the 70% at 11 1/6 inch is actually 1/64 inch more conservative.

mountainwalker

Thank you all for all the helpful answers. RoadTire what did you mean by the bottom of your chart by "No. Links/x2 Pins"?

RoadTire 

A reminder to me that a link is 2 pins apart, (count every other pin if need be) not pin-to-pin, which is 1/2 link.

curbtender

Like mentioned, take the slack out of the chain.

LesterOfPuppets

The bottom row of chart is for when you don't have a ruler that will measure PAST 12".

Many think of a "link" as an inner "link" + an outer "link", or one inch. So if you have pins that line up on the 0 and 7 1/16" marks (14 pins apart) then your chain is toast.

mountainwalker

Thank you. This helped me catch some chains that needed to be replaced, in time before harm done.

RoadTire 

For simplicities sake I was thinking that all I have to remember if I'm off somewhere w/o a chart is "11-10-7," and "1/16." Or, "Ok - Toast - Lost Cause"

RoadTire 

*pffft* Duplicate post.