Thanks Dave.
The entry level mountain bike is not cassette style, it's actually a freewheel design with 7 gears at back and 3 gears at front. The bike had totally frayed rear shifting cables attached to it and missing front shifting cable when it was handed over to me. [IMG]cyclingforums.com700Open ↗[/IMG]
I did several spin under as is condition, and didn't notice any wobbling. At that time, the gear was: Front-middle chainring; back-5th cogs. Chain shows no wear yet (according to the wear indicator), and I observed no noticeable wear on the chainring nor freewheel itself.
Since it was equipped with quick release, so I took the wheel off and cleaned the rear freewheel first.... anyway, long story short, now that I've set it up all new cables (done with proper adjustment/test ride/ shifting is fine although not 100% perfect), the wobbling is very obvious. I just don't understand how I could missed the wobbling the first time?? ....
Could it be during my cables setup, or ... when I put the wheel back I messed up something that contribute to the wobbling(??)... but I watched a lot of other YouTube videos - hope I'm right - I don't think the wobbling can cause by setting up the cables or removing/re-installing the wheel (it tight and snugged in the dropout), am I correct??