Converted to friction shift! As you can see I also removed the old grip shifters and gained some real estate space on the bars. I'm probably going to get some more grip tape to cover up the bare bar.
I haven't ridden it yet but bench testing it, shifts are much quieter, faster, and more direct.
Bike has 94 miles on it now and has had no further problems. A friend of mine recently bought a Denali too, only his was preassembled at Wal-Mart. Aside from derailleur adjustments, I actually found everything to be pretty well tightened down and solid. But this thread is not about his bike.
Going on a group ride tomorrow morning which I'm sure will take it over 100 miles. Additionally I am going to take it on a test drive here in a bit to see how my new shifters work, probably 1-1.5 miles max, just far enough to make sure it works and try to get used to it.
Only other thing I've done is add a second water bottle cage for group rides.
EDIT: Just came back from a test ride. It shifts GREAT. Super smooth and fast, and extremely precise. What a massive improvement, and the stock shifters weren't THAT bad.
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