Slight Rear Cassette Cogset Noise in One Middle Cog - Plating Failure
11-07-18, 09:26 AM
#1
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Slight Rear Cassette Cogset Noise in One Middle Cog - Plating Failure
There has been a subtle rear cassette cogset noise when using the middle gear.
It was not possible to adjust the rear derailleur to decrease that small noise.
When I removed and disassembled the rear cassette cogset I discovered that the plating on that cog was flaking off.
It is funny because all of the other cogs are in pristine / new condition, except for this cog.
A replacement SRAM rear cassette cogset has been ordered to exchange for this part.
It was not possible to adjust the rear derailleur to decrease that small noise.
When I removed and disassembled the rear cassette cogset I discovered that the plating on that cog was flaking off.
It is funny because all of the other cogs are in pristine / new condition, except for this cog.
A replacement SRAM rear cassette cogset has been ordered to exchange for this part.
11-07-18, 10:04 AM
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Flaking off plating isn't uncommon at all. I've seen it on about any brand of cog that has been made with a plating.. SunTour, Shimano, Sachs/SRAM come to mind. While I don't keep my most worn out cogs I bet I have a dozen or more cogs with this flaking in my old parts boxes. I can't say that I've ever attributed the flaking with any performance issue and I have continued to use said cogs long after the flaking was first noticed. I do clean and service my chains and cogs a few times each season, have done so since I had easy access to a parts cleaner (back in the late 1970s). Si I've monitored cog wear on dozens of cog sets a few times a year for about 40+ years. And this is only the personally used ones, as a life long shop wrench this count can be increased many times over if my customer cogs are included.
Is flaking the usual? Certainly at the point, the tooth face, of contact the plating is removed. Whether by tiny flakes or by the grinding action that a chain roller has on the tooth face the cog surface is eroded away (otherwise cogs would never wear out). Why the plating sometimes also flakes off the cog sides is likely due to the in factory prep or plating treatments. Perhaps the cleaning wasn't as stringent on that batch as usual. maybe the plating solutions were somewhat off chemically. Perhaps the electrical current was not perfect. Or maybe the cogs were just removed too soon from the bath. Not being a surface treatment engineer I don't know if the plating was too thick or too thin for flaking to be more likely.
But I strongly suspect that the plating will be considered a cosmetic issue by the manufacture. Much like paint has a different warranty coverage (bad pun) then the joining of the tubes (that make a frame) has.
I do think replacing the cassette (and I hope the chain at the same time) will change the perceived noises. Andy
Is flaking the usual? Certainly at the point, the tooth face, of contact the plating is removed. Whether by tiny flakes or by the grinding action that a chain roller has on the tooth face the cog surface is eroded away (otherwise cogs would never wear out). Why the plating sometimes also flakes off the cog sides is likely due to the in factory prep or plating treatments. Perhaps the cleaning wasn't as stringent on that batch as usual. maybe the plating solutions were somewhat off chemically. Perhaps the electrical current was not perfect. Or maybe the cogs were just removed too soon from the bath. Not being a surface treatment engineer I don't know if the plating was too thick or too thin for flaking to be more likely.
But I strongly suspect that the plating will be considered a cosmetic issue by the manufacture. Much like paint has a different warranty coverage (bad pun) then the joining of the tubes (that make a frame) has.
I do think replacing the cassette (and I hope the chain at the same time) will change the perceived noises. Andy
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AndrewRStewart
AndrewRStewart
11-07-18, 10:23 AM
#3
Banned
a pretty face
Downside of wanting it shiny.. in the package,
the black steel is same as what's under the chrome..
the black steel is same as what's under the chrome..
11-14-18, 02:01 AM
#4
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Thread Starter
The SunRace CSR86 8AS 11-28 Rear 8-Speed Cassette has been replaced with a SRAM PG820 11-30 Rear 8-Speed Cassette.
The existing chain was used with this slightly larger cog and initially looks to be working fine.
The Shimano Claris R2000 Series has these instructions for sizing the chain length. On my setup, put on the largest sprocket and on the largest chainring, bypassing rear derailleur, determine the minimum length, then add two links. With this larger cog, I am half a link too short after switching from an 11-28 to an 11-30. It works, but I'll go with a slightly longer chain.
The black MTB cassette was selected / installed on this road bike.
SRAM 11-30 (Black) and SunRace 11-28 (Nickel)
SunRace 11-28 on Largest Sprocket and Largest Chainring
SRAM 11-30 on Largest Sprocket and Largest Chainring
The existing chain was used with this slightly larger cog and initially looks to be working fine.
The Shimano Claris R2000 Series has these instructions for sizing the chain length. On my setup, put on the largest sprocket and on the largest chainring, bypassing rear derailleur, determine the minimum length, then add two links. With this larger cog, I am half a link too short after switching from an 11-28 to an 11-30. It works, but I'll go with a slightly longer chain.
The black MTB cassette was selected / installed on this road bike.
SRAM 11-30 (Black) and SunRace 11-28 (Nickel)
SunRace 11-28 on Largest Sprocket and Largest Chainring
SRAM 11-30 on Largest Sprocket and Largest Chainring
11-14-18, 10:06 AM
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And the black is but one more type of coating. One that tends to not flake off but still is a coating that wears. Andy
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AndrewRStewart
AndrewRStewart
11-14-18, 11:21 AM
#6
Senior Member
A couple years ago I had a mysterious noise on two middle cogs only, could not adjust it away no matter what. Eventually I went to remove the cassette for further investigation and I immediately discovered the cassette retaining ring was not very tight. I tightened it up properly, put the wheel back on, checked the derailleur adjustment and problem solved.
