When to replace a Record chain?

[terrytnt]

My LBS says it depends... mileage of course, how clean you keep, type of riding, weather conditions, chain flex, etc.

As a rule of thumb I heard 2-3K is about the time to replace a record chain. I ride 150 miles each week, keep my drive train clean and well lubricated, avoid riding in rain, but don't really know how to check for chain flex.

any ideas from you pros out there...

[Dave]

I've studied chain and cog wear quite a bit over the last several years and discovered some facts that don't agree with commonly recommended methods of determining when a chain is worn out or how to maximize cog life. I'll repost the long story. If you find either elongation or roller wear to be near the limits after 2-3K, then your maintenance technique needs improvement.

None of the common chain wear measuring tools produces an accurate measurement of chain elongation (change in pitch) because they add roller wear to the measurement and most measure over a very short length. The roller wear can be as large as the elongation over this short length, so the tool may report twice the actual elongation. The result may be a chain tossed when it's half worn.

The best way to measure elongation is with a 12" scale. Place an accurate 12” scale on the edge of a pin. The pin at the opposite end will be totally covered when the chain is new. As the chain wears, this pin will begin to “peak out” from under the scale. Change the chain before ½ of this pin is exposed. The maximum allowable wear is 1/16” (.063”) per foot. One half of a pin is slightly more (.070 inch).

Elongation is only half of the chain wear issue. The rollers also wear - often as much as 20 times more than the pins and bushings (which cause elongation). New rollers will measure about .205 inch in between them. When this distance increases to .235-.240, I consider the chain to be shot. It is possible to have this much roller wear and very little elongation.

Changing a chain long before either of these wear criteria is met is not likely to increase cog life. It's entirely possible to wear out at least one or two cogs over the life of a single chain. I've used a single chain for 6000 miles, and worn out one cog, even though the chain showed little elongation. The only practical way to detect a worn cog is by installing a new chain. If the chain skips on a cog, while pedaling under a heavy load, then the cog is too worn to use with a new chain.

The best way to maximize cog life is to alternate the use of two (or more) chains, changing every 1-2000 miles. With this method a new chain will never be installed on worn cogs. When both chains are worn out, then most likely the cassette will be too. There might be a valid argument for including a third chain, but it all depends on the cost of the chain relative to the cost of the cassette. For example, if chains cost $40, the cassette cost $120, and chain life is 4000 miles, the cassette could be used for 8000 miles. The cost per mile is 2.5 cents. If a third chain was included in the rotation, the cassette might be useable for 12,000 miles and the cost drops to 2 cents per mile.

After measuring several chains, I know that mine will never come close the maximum elongation, even if used for 6000 miles. For that reason, I don’t even bother measuring elongation any more. I have a home made plug gage, made from a 6mm hex wrench, ground down to .070 inch thick. If it drops between any two rollers, the chain is shot and I trash it.

[BoulderGeek]

Is replacing a chain earlier a good way to prevent against chain breakage?

I have snapped several chains (Shimano 9 and Wipperman 9) over the years. It's painful and dangerous, and I have now developed a bit of a phobia about it when I am putting the power down on climbs.

The Shimano 9-speed chain and Sram 9 cassette that were new before I went to Europe are now showing skipping under pressure in a few cogs. I estimate 1500 to 1800 miles on these (don't really know as I didn't ride with a computer this summer, just GPS, but not every ride).

I'm thinking a swap before 2000 miles might be in order. Is this on target or is it poor rationale?

[terrytnt]

These are all great points. Considering that record cogs are expensive, perhaps changing the change every 2000 makes sense.

For that matter, how long will record cogs last. And what do you look for. Have 3500 miles from last year and already 3000+ this year without any real problems shifting. Would it be unusual to go 10,000 on record cogs???

[Dave]

Is replacing a chain earlier a good way to prevent against chain breakage?

I have snapped several chains (Shimano 9 and Wipperman 9) over the years. It's painful and dangerous, and I have now developed a bit of a phobia about it when I am putting the power down on climbs.

The Shimano 9-speed chain and Sram 9 cassette that were new before I went to Europe are now showing skipping under pressure in a few cogs. I estimate 1500 to 1800 miles on these (don't really know as I didn't ride with a computer this summer, just GPS, but not every ride).

I'm thinking a swap before 2000 miles might be in order. Is this on target or is it poor rationale?

You might want to read and digest what I've posted. Chain wear is not difficult to measure. A chain shouldn't start skipping after substantial use, barring a damage or stiff link. The cogs and chain wear-in to fit together. Skipping almost always occurs only when a new chain is installed on old cogs.

As fas as "snapping" a chain, the method of prevention depends on what actually failed. Wipperman produced some defective stainless steel chains that suffered from cracks in the outer plates and subsequent breakage of the outer plates. Not much you can do about defective product. The other common failure mode is a pin simply pulling out of the side plate. If it occurs at a shimano replacement pin, then the pin may not have been installed properly, or perhaps it was just a bad pin. I prefer to use a wipperman connex link to rejoin a chain, but can't tell you for sure if the wipperman 9 speed connex link fits correctly. A shimano 10 chain requires the Campy version of the wipperman 10 connex link for a good fit.

[jsfoster]

does one need to have the special Campagnolo chain tool for the new 10 ultra narrow chains, or will a good park tool do as well?
Thanks, Jon

[justinf]

The Park tool is fine in my experience.

[jsfoster]

The Park tool is fine in my experience.

Thanks, I'll try it

[Dave]

does one need to have the special Campagnolo chain tool for the new 10 ultra narrow chains, or will a good park tool do as well?
Thanks, Jon

If a Park tool is used, it's critical to eliminate the tension on the chain by draping it over the BB shell while the pin is installed (from the left side). If you don't, the tension will pull the guide pin crooked and likely result in a failed installation.