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05-02-14, 04:06 PM
#6
seeker333
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Join Date: Feb 2004
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Originally Posted by Tandem Tom
While touring how long do you get out of chain? Just replaced mine yesterday after about 2,500 miles.
The general rule on chain stretch (erosion actually) is 1%; that is replace chain when length increases 1%.

This works out to 1/16" in 12 links (12x0.5" chain pitch=6", or 1/16/6*100=1.04%), or 1/8" in a foot of chain (24 links), or 1/4" in 2 feet of chain (0.25" in 24").

I personally measure stretch by hanging a degreased chain from a small nail on a wall, measuring 24" from a pin to the next pin @ 24"+ away, and the extra length >24" is the amount of "stretch", usually 1/8-1/4". Measuring across a greater length makes it easier to ascertain the small amount of stretch. Hanging the chain works better than laying it on a bench, since gravity takes all the slack out and gives you a truer measure of elongation.

I've found that a brand new chain usually measures 24 1/16" long for 48 links right out of the package. There is a small amount of play even in a brand new chain, so you start out with 1/16/24*100=0.25% stretch before you've even ridden the new chain.

I usually retire my chains at 0.50%-0.75% stretch (1/8-3/16" in 24") because I find the chainrings and cassette cogs are already showing signs of wear at this point.

The whole point of measuring and replacing the inexpensive steel chain is to prevent premature wear of the more expensive rings and cassette.

I've gotten 20,000-25,000 miles chain life on unloaded road bikes using the above guidelines, plus a serious chain cleaning/lubing procedure. On tours you will get less because of the added load, plus it's harder to make time to fuss with bike maintenance regularly when you're on tour. Figure 5,000-10,000 miles for pavement touring with reasonable maintenance, and less on dirt sections.