San Rensho 

Is there a way to measure chain stretch without removing the chain? I seem to remember someone said there is a tool for measuring a link or a couple of links to measure stretch. Thanks.

urban_assault

from Sheldon Brown's website....Sorry Mr. Brown

Measuring Chain Wear

The standard way to measure chain wear is with a ruler or steel tape measure. This can be done without removing the chain from the bicycle. The normal technique is to measure a one-foot length, placing an inch mark of the ruler exactly in the middle of one rivet, then looking at the corresponding rivet 12 complete links away. On a new, unworn chain, this rivet will also line up exactly with an inch mark. With a worn chain, the rivet will be past the inch mark.

This gives a direct measurement of the wear to the chain, and an indirect measurement of the wear to the sprockets:

* If the rivet is less than 1/16" past the mark, all is well.

* If the rivet is 1/16" past the mark, you should replace the chain, but the sprockets are probably undamaged.

* If the rivet is 1/8" past the mark, you have left it too long, and the sprockets (at least the favorite ones) will be too badly worn. If you replace a chain at the 1/8" point, without replacing the sprockets, it may run OK and not skip, but the worn sprockets will cause the new chain to wear much faster than it should, until it catches up with the wear state of the sprockets.

* If the rivet is past the 1/8" mark, a new chain will almost certainly skip on the worn sprockets, especially the smaller ones.

2 wheeler

Great bit of info!!

urban_assault

He says it in a much more eloquent and concise manner than I ever could.

cyclezen

Park Tool - chain wear indicator CC-3 - is a 'go-no go' measuring device that tells you if the chain is at 3/4% or 1% wear. At $9-$11 (depending where you buy) itz a huge rip-off... until you start trying to stretch your chain properly and hold the dam ruler up to the pins, without a hi-intensity lite (senior moment), while barely being able to read the ruler - to measure for the 1/16" stretch that says "replace me".
CC-3 - avg old guy eyesight okay, low light approved, no need for octopus arms
I hate spending ten bucks on a flat piec O metal - then, yesterday, I checked all 5 bikes in about 30 secs, one needed a new chain - did that this morning...
I hate convenience... Bah, Humbug

slvoid

Get a pair of calipers, measure 6 links, from end to end, it should read 6.000 inches give or take 0.005 or so.
Technically 12 links = 12 inches but most people don't have calipers that are 12".

2 wheeler

The price of the Park tool isn't too bad, if you think about the money you might save by replacing a chain before it eats up $50 to $100+ in chain rings and casettes. I think I'll add one to my growing list of stuff I just gotta get!

jemoryl

Last time I replaced a chain I hung the old chain on a nail next to a new chain. The more links you can compare, the more easily you will be able to measure the stretch. So if you look at the 24th link, you should be able to see an elongation of 1/8" quite easily - this would correspond to a 1/16" elongation for 12 links.

jazzy_cyclist

+1. Pretty much foolproof.

San Rensho 

Thanks to all.