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Discussion Starter · #1 ·
Well, my chain got in between the cassette and the spokes. The rear derailleur was adjusted fine, but I was shifting up a bunch of cogs on a steep climb. The chain was lodged in there pretty good, and I had to hike out. When I got home, I popped off the cassette, and the outside spokes were all torn up. Anyone know the length of the spokes on the drive side? The spokes area bent pretty good and I'm not sure I can get a proper measurement.
 

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Bend them as straight as you can for a measurement. Spokes are offered in 2 mm increments anyways, so it's not like you need to be incredibly precise.

Also, do tighten the L-screw. Seems to me it was loose.
 

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Discussion Starter · #3 ·
Bend them as straight as you can for a measurement. Spokes are offered in 2 mm increments anyways, so it's not like you need to be incredibly precise.

Also, do tighten the L-screw. Seems to me it was loose.
Thanks. Also just realized that since I'll have to rebuild the wheel, I can take out one of the inside spokes and measure it. I wasn't thinking clearly earlier.

I'm pretty anal about my bikes and am sure that the derailleur was adjusted properly. I just did a 6 hour endurance race without any problems. I think it was when I tried to shift up too many cogs too quickly that the chain fell off.
 

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Thanks. Also just realized that since I'll have to rebuild the wheel, I can take out one of the inside spokes and measure it. I wasn't thinking clearly earlier.

I'm pretty anal about my bikes and am sure that the derailleur was adjusted properly. I just did a 6 hour endurance race without any problems. I think it was when I tried to shift up too many cogs too quickly that the chain fell off.
If the RD is properly adjusted the chain will not just drop into the spokes, no matter how fast you shift it.
 

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Discussion Starter · #5 ·
I must admit that I have not checked the adjustment of the derailleur since the race, so I was probably to blame. This is the first time throwing a chain on or off road. Anyway, if anyone is interested, the DS spokes on the rear wheel is 290mm.
 

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I must admit that I have not checked the adjustment of the derailleur since the race, so I was probably to blame. This is the first time throwing a chain on or off road. Anyway, if anyone is interested, the DS spokes on the rear wheel is 290mm.
Its likely that your RD hanger was bent inward somehow, allowing the chain to shift past the 36T cog and into the spokes. If the L limit screw was adjusted properly and didn't give you any issues during a 6 hour race, then the hanger became bent sometime after the race. You should check it to ensure its straight so that this doesn't happen again after you've repaired the wheel.

Jeremy
 

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Discussion Starter · #7 ·
After mounting the rebuilt wheel, I checked the rear derailleur adjustment. The L-screw was totally off. The derailleur cage went past the largest cog by at least half the width of the chain.
 
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