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Day: August 22, 2009

Damaged Inner Plate on SRAM PG870

Published August 22, 2009

I’m really unsure how this happened, but this is why the aformentioned chain link is stuck. It seems that the very end of one of the steel inner plates had some metal torn away from it, and this metal was then pushed between it and a roller, wedging the roller and link in place.

As this is the very end of a plate, it couldn’t have happened from hitting something. I can only figure that either a manufacturing defect which left a bit of metal flashing sticking out was finally hammered down into place, or maybe a rock or piece of metal or something got on one of the teeth and during a sudden/hard pedal stroke it cut the plate. While the cassette is steel and may have been strong enough to do this, the chainrings are aluminum and likely couldn’t make this happen. I’ve also looked over all of the teeth and they all appear to be in good shape without any exceptional burrs or dented spots.

Later tonight after eating dinner I’ll try to get the bit of metal out, in hopes of salvaging the chain. If this doesn’t work I imagine that tomorrow will also include a quick run to REI for a new chain.

UPDATE: Removing the offending link and dropping in a spare (which I’d forgotten that I had) seems to have sorted it all out.

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Stuck Link!

Published August 22, 2009

Today I took a ride from my house up to Stony Creek, around the trails, into Downtown Rochester, then over to Bloomer. Bloomer is a bit convoluted, and the only trails that I could find are the rather intimidating ridge trails, which are a bit riskier than I prefer to ride. (See this photo, which shows where I stopped riding as I prefer to not duck around chest-height trees on off camber bench cut trails with steep drop-offs.)

Right as I began heading towards my house, something wasn’t going right in the drivetrain. Every couple pedal strokes or so I was getting a bit of ghost shifting, particularly when in physically smaller gears. A quick look showed that it was likely a stiff link on the chain, so I headed back towards home. En route to home things became worse and worse, to the point where I could only ride in the big ring and somewhere above the middle of the rear cassette. Regular ka-chunk sounds were heard as the derailleur jumped around a bit.

By the time I got home there were 34.37 miles on the odometer, in just about 2:49. I was rather wanting to ride more, but the chain was saying otherwise. This is a pretty new chain, and prior to this ride (at about the 120 mile mark) the factory lube still seemed to be doing its job. Everything was moving very smoothly, there was no noise from the chain, and everything was shifting well. Right now I’ve got the chain soaking in degreaser, and then post-cleaning I’ll give it a bunch of (physical) attention to try and loosen up the link. At least a new chain isn’t particularly expensive if that doesn’t work.

(The bandage is from cutting a good slice mostly off of my finger tip yesterday while slicing limes with a bent, dull knife. Doing this made me very mad at myself.)

UPDATE: Problem found! It’s a damaged inner plate.

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