About six months ago, my fantastic ASR-5 (a.k.a Best Bike Ever Made) developed a creak while pedaling. Sometimes it was a creak and sometimes it was a definite knock. It wasn't just under hard pedaling, either. It happened with moderate or even light pedaling.
I tried the basic stuff -- cranks, shock pivots, derailleur hanger, and nothing helped. But it wasn't consistent. Sometimes it would creak loudly, sometimes it would knock loudly, and sometimes it was silent.
But it's been getting worse lately so I took more aggressive actions and disassembled the entire shock linkage area, including the dogbone. That's when I found the problem. With the shock and dogbone completely removed and the rear wheel supported by a rope tying it to the seatpost, I could produce the knock simply by pushing the (now disconnected) carbon seat stays side to side. The only thing connecting the rear triangle to the bike, at this point, is the bottom pivot. I'd never touched that.
So I removed the crank, removed the bottom pivot, cleaned, lubed, and tightened everything back. Silent once again!
That said, I think I know what specifically caused the knock. The right bearing in the bottom pivot felt a bit loose as I was cleaning. I couldn't pop it out by hand but it definitely wasn't as tight as the left bearing. I'm not sure how long this "fix" will last but I'm wondering if I need a rebuild kit for new bearings or if the actual rear triangle is worn at that point. the bike has about 1500 miles on it -- all dirt, all singletrack.
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