Weird sounds from Sram GX crank / shifters? When moving the chain backwards while bike is standing, I hear some weird sounds.. I made a playlist on youtube and would greatly appreciate some help :(. Video titles give more details.
Should it matter, crank and shifters are Sram GX. Rear is type 3 with roller bearing clutch. Crank also has bearings I think.. I am thinking they might cause the sounds :(
Also, the front shifter is badly aligned. However, I was noticing the issues in the 1x7/8 video (frequent sound + chain bump) even if I lifted the chain so it clearly had no contact with the shifter cage.. I think it is the crank's fault.. maybe the bearings.
https://www.youtube.com/playlist?list=PLLyaOLAXFko4YjPCAMDDVqRE6C05b7waA
More often than I would like I also hear a snapping sound coming, I think, from the inside... I thought it is from the crank and might be related to the sounds/symptoms seen in the videos.
All of the rattling and popping appears to be coming from chain rub on the front derailleur, poor rear derailment indexing, and the chain jumping on the rear cassette sprockets.
You seem to have convinced yourself that the noises are caused by the crank bearings. That's highly unlikely and easily disproved. Take the chain off the chainrings and spin the crank - you should not hear any noises. Also check for play in the bottom bracket bearings and any 'notchiness' as you spin the crank.
To address the drivetrain issues, first check the chain is not over-worn (there are ways to estimate this but a $10 chain wear gauge is a good investment). Also check sprocket wear.
Check your front and rear derailleur setup. The Park Tool Repair Help site has easy to follow, comprehensive guides.
https://www.parktool.com/blog/repair-help/rear-derailleur-adjustment
https://www.parktool.com/blog/repair-help/front-derailleur-adjustment