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Discussion Starter · #1 ·
Hi,

Got a wierd problem on my (up until now) trustworthy 04' Ninja Turner - the 2nd biggest ring on the cassette keeps getting twisted. I've switched 3 cassettes already - the first held for a year until it happened. The 2nd for 4 rides. The 3rd for one ride. All were good cassettes (XT, SRAM 990).

My mechanic doesn't have a clue what might be causing this. He claims it could be force i'm applying - but nothing out of the ordinary happened, and the first one DID hold for a year, and it doesn't happen on any of my other bikes.

what can be the cause of something like that? Should i keep looking, change another cassette? change the chain? what?

thanks,
Lior
 

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You're not supplying enough info, like your riding and shifting style, including which cassette was the latest to bend. How much do you weigh? Do you have lots of steep climbs?

What could do it is an on power drop to 2 or the same going from 3-2. The gears on 9spd are generally weaker, too. My 300 pound friend uses a bottom of the line cassette and it works fine in terms of durability.
 

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Discussion Starter · #3 ·
Ok, more details

Jerk_Chicken said:
You're not supplying enough info, like your riding and shifting style, including which cassette was the latest to bend. How much do you weigh? Do you have lots of steep climbs?

What could do it is an on power drop to 2 or the same going from 3-2. The gears on 9spd are generally weaker, too. My 300 pound friend uses a bottom of the line cassette and it works fine in terms of durability.
The bike are not currently here (at the store) so i can't add a photo.

I weight around 70kg (160 pounds i think). I ride most of the time at middle ring up front and 2nd or 3rd at the rear. The bend is always on the 2nd biggest ring on the rear (the one i'm mostly use). All my cassettes were 34 (the first two had a nice jump from 2nd rear to largest, the last one being 06' sram, had a slighly closer gap).

I do ride an oocasional steep climb.

However, i'm not quite sure it's my fault. I haven't changes style in quite a while, and as i said, it happens only on one pair and not the other 2, while on my hardtails i ride VERY steep hills (rear XTR cassette) and on the other hardtail (Santa Cruz cham, almost the same angles as the 5 spot) i ride the same steepness of hills, and nothing happens.

Shouldn't it be one hell of bad gear shiifting to destroy a cassette on it's first ride?

The bending, btw, seems to be slowly happening and not one strike that bends it all the way.

thanks,
 

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Put one of the cassettes on from the other bikes and see if it goes bad or not. If it does, it's something with your frame. I'd guess some of the pivots are loose or worn causing the rear to go out of alignment under torque.
 

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Lior,

I just noticed something in my garage that might be cause this type of problem. I have a couple of racks that my kids use to hold their bikes up. They look like this:

http://www.dero.com/floor_rack.html

I backed one of my bikes in to temporarily hold it up and the bar from the rack wedged right up against the back of the cassette. It gave me a shock and I removed the bike immediately. It could easily do the kind of damage you discribed.

Any chance the cassette is getting damaged from something other than riding?

-John
 

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Discussion Starter · #6 ·
SUB160 said:
Lior,

I just noticed something in my garage that might be cause this type of problem. I have a couple of racks that my kids use to hold their bikes up. They look like this:

http://www.dero.com/floor_rack.html

I backed one of my bikes in to temporarily hold it up and the bar from the rack wedged right up against the back of the cassette. It gave me a shock and I removed the bike immediately. It could easily do the kind of damage you discribed.

Any chance the cassette is getting damaged from something other than riding?

-John
It DID start once i installed a THULE on the roof of my car, but i see nothing even remotely close to it..
 

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Is your chainline pretty straight or is the middle ring causing the chain to pull the cassette cog outward too sharply? Did you try a different chain? I know a lot of guys heavier than you who don't bend the 5-arm XT cassettes, so it seems unlikely it would be sheer pedal power.
 

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tscheezy said:
Is your chainline pretty straight or is the middle ring causing the chain to pull the cassette cog outward too sharply? Did you try a different chain? I know a lot of guys heavier than you who don't bend the 5-arm XT cassettes, so it seems unlikely it would be sheer pedal power.
...also, check your rear alignment using the old string test. Mis-alignment could add to the potential for bending, with an existing questionable chainline.
 

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There was a guy who used to come into our shop with the same problem on his road bike. It was a combination of what tscheeeeeeeeeesie said and the fact that the guy hardly ever shifted. We put a narrower spindle BB on his bike and a little arrow made out of yellow electrical tape on his handlebar that pointed to his shifter.

Definitely check your chainline and use that granny gear every once in awhile and see if that helps.
 

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I had the same problem with my flux. After checking all the pivots chain line ect...It turned out that my derailleur hanger was slightly bent. The bend was so slight I couldn't see it until I layed the hanger on a flat surface. Swap your hanger.
 
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