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Cassette/Derailleur Problem(5 posts)

Cassette/Derailleur ProblemMe Dot Org
Aug 29, 2002 7:04 PM
I have a Campy Racing Triple Drivetrain (about 7,000 miles). Recently I've been getting very sloppy shifts off the middle gears of the cassette - doesn't seem to matter what ring I'm on in front. Chain shows moderate wear, I've tightened the cable, barrel adjuster and limit screws appropriately.

Any suggestions as to where to look next? I'm just a bit stumped, as my shifts on the big and little cogs seem fine, it's only the middle ones that are giving a problem...
Sounds like the chain.High Gear
Aug 30, 2002 3:16 AM
Chains don't just wear length wise but side play as well. When you shift, the derailleur is moving the chain over at that point but the side slop is not letting it engage with the cog. It makes sense that it is shifting ok on outer ends of the cassette when the chain has an angle to it. You can also adjust the "B" screw so that the top pully on the derailleur is as close to the cog as posible to help shifting too.
Put my money on a worn cassette.Spoke Wrench
Aug 30, 2002 5:39 AM
Those are the gears that you use the most, right? Then those are the gears that will have had the most wear.
How to determine worn cassette.Rubberbandman
Aug 30, 2002 12:06 PM
How do you know when a cassette is worn? What do I look for?

Thanks,
BBR
Wears with chainKerry
Aug 30, 2002 3:42 PM
Your first problem is that you posted this on the general forum instead of the components forum, and as a result it probably will be off the bottom before you read this. But here goes.

You say that the chain only shows "moderate wear." Since chain wear is pretty much defined by elongation %, can we presume that you have actually measured it and know the number? 0.5% is worn out. In my experience, when a chain reaches that point, you have to at least replace your frequently used cogs as well. If the cogs show any "shark fin" shape, then they must be replaced. Another good way to tell if they need to be replaced is to install a new chain and then really stand on it in the suspect cogs. They will likely skip.

The math on chain/cassette replacement (for me) looks like this. Campy 9 speed chain, $25, Chorus 9 cassette $60. Total miles, 10K. Cost per 100 miles = $0.85.

The math for people who say to replace the chain every 2500 miles to avoid wearing the cogs too fast: DA chain $24, DA cassette, $75. Assuming ZERO cassette wear (bad assumption), cost per 100 miles = $.96.