Cassette wear

[LegendRider]

Rohloff makes a tool for determing wear on your cassette. But, I understand that it will not work on narrower 10 speed cassettes. Is this true? Is there an alternative? With the prices for cassettes these days, it seems like there should be!

By the way, please don't tell me to track the mileage on my cassette - there is no way I can keep track of it... ;)

[Dave]

A cassette is worn out when it will no longer mesh properly with a new chain and chain skip occurs. Unless the cogs are far more than just worn too much to mesh with a new chain, you should never suffer chain skip with the chain in use, just before that last new chain was installed and the chain skip occured.

If you really want to get the maximum life from a cassette, you can do that by alternating the use of several chains, so a new chains is never installed on worn cogs. The number of chains to put into a rotation depends on the relative cost of the cassette and chain.

Ti cogs may last half as long as steel cogs, so if you know that your most-used cog is among those Ti cogs on a DA or Record cassette, then don't expect very long cog life. I do a lot of climbing, so I know that my most used cog is either the second or third from largest and it would be Ti, so I always buy all steel cassettes.

If you're one of those folks who constantly swaps cassettes or wheels among several bikes, the best ting you can do is get 3-500 miles of use on your chains, while the cassette is new. I've proven that a chain with only a few hundred miles of use will not skip on moderately "worn out" cogs, but a new chain will.

[LegendRider]

Dave,

Thanks for the detailed response. Here's the issue - I have a DA 7800 cassette and chain on one bike. I have no idea how many miles are on the cassette (more than 1k and less than 5k) and the chain is at .75% stretch according to both types of Park chain checkers. So, should I buy a new chain and risk skipping if the cassette is, in fact, old and worn. Or, should ride them both into oblivion?

[Dave]

That chain checker tool is lying, so the actual elongation may be .5% or less. I would install a new chain and try it. Shimano chains are cheap (good thing because they don't last long). If you get chain skip on one of the cogs, then you can decide whether to buy a new cassette or put the old chain back on. If none of the cogs skip while pedaling under a heavy load, you're good for the life of that chain.

The proper way to check elongation is with a 12" machinist scale. Lay one end on the edge of a pin. If the pin at the opposite end is exposed by nearly half it's diameter, it really is elongated .5%.

[fierte_poser]

Lots of choices, but here is a suggestion:

1) Buy a new chain and install. Use with old cassette. Two possible outcomes:

--> No chain skip? Ride this new chain (#1) for 500 miles, then remove #1 and install a new chain (#2) and ride #2 for its useful life. When #2 is done, install #1 again and ride for its useful life. Since you put some wear on chain #1 today, it should mesh with the worn cassette down the road.

--> Chain skip? Buy a new cassette. Break in a couple of new chains for 500 miles each on the new cassette. The new chains should now mesh with both the old cassette and the new cassette. If they don't mesh with the old cassette after 500 miles of breakin, the old cassette is toast.

Make sense?

[djg21]

Dave,

Thanks for the detailed response. Here's the issue - I have a DA 7800 cassette and chain on one bike. I have no idea how many miles are on the cassette (more than 1k and less than 5k) and the chain is at .75% stretch according to both types of Park chain checkers. So, should I buy a new chain and risk skipping if the cassette is, in fact, old and worn. Or, should ride them both into oblivion?

Change your chain every 1,500 miles. It may be overkill, but you will be far less apt to wear cogsets, and you encounter fewer problems doing wheel swaps.

[Brian Smith]

Rohloff makes a tool for determing wear on your cassette. But, I understand that it will not work on narrower 10 speed cassettes. Is this true? Is there an alternative? With the prices for cassettes these days, it seems like there should be!


Mark -
I have the rohloff tool, seen here:
http://www.rohloff.de/en/products/hg_ig_check/index.html
I haven't tried it on 10 or 11 speed cassettes yet, so I'm not sure that it doesn't work for them. I suspect that the length of chain that comes with the tool is a wider-than-current chain, perhaps creating the idea you've heard that it won't work for 10-speed cassettes.

The tool was/is great, in the shop, when it worked/works with current cassettes. With the tool, a cassette that is worn, but not yet worn enough to cause skipping, is able to be identified as such. When you discover that your cassette is worn, even if it's not worn to the point of enabling skipping with a new chain, you have 2 options: firstly: continue to use that cassette and experience reduced lifespan for any chain, new or used, upon it, or secondly: replace the cassette to maximize any new chain's life.

Even if you can "get away" with using a newer chain on a used cassette, if the cassette has worn somewhat, the index shifting performance of the system will be lower than if both components were new, so it sometimes depends a bit upon what you're after, in deciding whether or not to replace the cassette. Suppose the bike in question is strictly a training mule with which you ride mostly alone, and slow shift performance and poor shift performance under load are not as important concerns as are getting the most miles per dollar spent on upkeep. Perhaps for that kind of bike, it is worth applying new cassettes only when new chains skip on them. With almost any other sort of goal, I find it better to replace chains long before any of the chain indicators suggest that they're used up, and before the cassette checker inidicates that any of the cogs (check them all, not only the smallest!) are worn. With this regimen, you can usually get into your third chain before you detect cassette wear, at which point it becomes useful to move that chain/cassette system onto a training mule, or run it until you wear it out to your satisfaction and replace the pair of components as a set.

[Velosmith]

Great responses all. But, do you really expect a cassette to be worn at 1k to 5K?

OK I'm not a Shimano guy however, I would expect most anything to last longer than that with normal chain care. I'm pretty sure I get more like 10k-15k.

[Dave]

Great responses all. But, do you really expect a cassette to be worn at 1k to 5K?

OK I'm not a Shimano guy however, I would expect most anything to last longer than that with normal chain care. I'm pretty sure I get more like 10k-15k.


FWIW, I used one chain for 4,000 miles with a Record cassette and did a lot of climbing with a 28T chainring that creates more chain tension than a 39T ring would. The 19 and 21T Ti cogs were extremely worn at that point. I got major chain skip when a second chain was installed.

Another bike with the same drivetrain setup, but using steel cogs, only wore out the 19T in about 6,000 miles, despite the chain showing a small fraction of the "allowable" .5% elongation. The rollers on that chain were quite worn, with the original .200 inch spacing between the rollers increasing to about .240 inch. A chain autopsy showed the OD of the rollers reduced by about .005 inch and the ID about twice that amount.

To avoid that problem in the future, I started alternating the use of several chains, rather than toss chains that were half worn. I expect to get 4-6,000 miles from a 10 speed chain and use three chains with one cassette, but the chains will each be alternated to avoid the skip.

[LegendRider]

Great responses all. But, do you really expect a cassette to be worn at 1k to 5K?


The Shimano ti cogs wear quickly and I climb a lot - did over 9k vertical feet today!