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Cat 6 rider
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3,119 Posts
Discussion Starter · #1 ·
I had an interesting problem- one which was driving me crazy. I finally figured it out. I’m posting it in case anyone else finds themselves with an impossible to diagnose rattle.

It only manifested itself when riding on rough roads at speed. I couldn’t get it to rattle when bouncing it, or on the repair stand. I stripped off the wheel reflectors, valve stem nuts and valve stem covers, brackets, and everything else I could and still ride the bike, no luck. That pretty much narrowed it down to the drive train, but it didn’t matter if the bike was under power or coasting, or what gear it was in. I couldn’t see any problems, even when riding with the sun to my side and watching the shadows. Then I checked for chain stretch, and gear wear- all negative. I reached back and held both the chain and derailleur with my foot while riding to see if I could isolate it- no change. The rear wheel had recently been replaced due to a spoke breaking warranty issue, so I shook and bounced it to see if maybe something had been left inside during manufacture- again nothing.

Have you figured it out? It was related to the new wheel. It’s also something the bike repair books say can’t happen. The cassette was loose, so loose in fact that the gears weren’t grouped tightly together and would rattle against each other. When the mechanic swapped the wheel he must not have tightened the cassette enough, and you don’t really have to torque them because pedaling tightens them anyway, right? I have almost 200 miles on it after the wheel replacement, including some fairly hard hammering and steep hills, but it just didn’t tighten up. And no, it wasn’t cross threaded. I guess there was a rough spot on the threads or a piece of grit on them, because after the wrench moved it smoothly tightened more than half a turn with very little effort. So I have a quiet bike again, even when going over brutal pavement.
 

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naranjito
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785 Posts
modern cassettes do not tighten themselves as you pedal. old style screw-on freewheels are. if you don't tighten the lockring enough, it can work loose, no matter how much or how hard you pedal.

foz
 

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Bad mechanic

California L33 said:
you don’t really have to torque them because pedaling tightens them anyway, right? I have almost 200 miles on it after the wheel replacement, including some fairly hard hammering and steep hills, but it just didn’t tighten up.
As foz said, this is absolutely incorrect. The cassette cogs slide on, and the lockring must be torqued to specification because there is nothing in the pedalling action that would tighten the lockring. Also, if tightened to spec., there is very little chance of a lock ring comming loose due to riding. The face of the lock ring is typically serated to prevent this from happening. Your mechanic did a poor job.

California L33 said:
And no, it wasn’t cross threaded. I guess there was a rough spot on the threads or a piece of grit on them, because after the wrench moved it smoothly tightened more than half a turn with very little effort.
The torque specification is typically 30-50 nm (22-29 ft-lb), and this is a lot of force. There's no way that a rough spot on the threads of a piece of grit would resist this amount of torque. Your mechanic did a poor job.
 

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Spacer missing?

On some wheels, ones that come with a spoke protector (Rolf Vector Comp for example) and you removed the protector and did not put a spacer in behind the cassette, the cassette will not be tight on the freehub, will jingle as you ride and sometimes just not shift right.
 

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Cat 6 rider
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3,119 Posts
Discussion Starter · #5 ·
Lone Gunman said:
On some wheels, ones that come with a spoke protector (Rolf Vector Comp for example) and you removed the protector and did not put a spacer in behind the cassette, the cassette will not be tight on the freehub, will jingle as you ride and sometimes just not shift right.
No spacer, just loose.
 
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