Hello, I'm having trouble with a popping sound that occurs when I apply a lot of pressure on the pedals and use level 3 or higher PAS level. This only happens on high gears when I'm riding slow and quickly accelerating. I believe the sound is caused by high tension on the chain, which happens occasionally when I forget to change gears before stopping or when in a rush. The popping sound occurs when I'm pedalling with pedal assistance on or sometimes just by using the throttle.
Before the sound occurs, I notice the bottom pulley stretches forward towards the chainring direction and then drops with a popping sound. I've ridden the bike for around 500 miles, and the bike and bafang bbs02 were new. I've checked the cassette, top and bottom pulleys, rear derailleur and chainring alignment, and they all look fine to me (please check the photos below).
I suspect that the problem may be caused by an improperly sized chain. I have a 1 x 9 drivetrain, and I'm using a 9-gear chain, but it doesn't look good when I shift it on the largest sprocket and my only chainring on the front. I believe that the chain may be too short and has stretched, causing the sprockets to slide off and creating this loud popping sound. Btw. all I'm still beginner in those subjects and probably make a lot of mistakes but I'm willing to learn anything related to bicycles and e-bikes
Here's a link to the bike specs: https://www.decathlon.co.uk/p/27-5-inch-mountain-bike-rockrider-st-530-mdb-black-yellow/_/R-p-341628
Before the sound occurs, I notice the bottom pulley stretches forward towards the chainring direction and then drops with a popping sound. I've ridden the bike for around 500 miles, and the bike and bafang bbs02 were new. I've checked the cassette, top and bottom pulleys, rear derailleur and chainring alignment, and they all look fine to me (please check the photos below).
I suspect that the problem may be caused by an improperly sized chain. I have a 1 x 9 drivetrain, and I'm using a 9-gear chain, but it doesn't look good when I shift it on the largest sprocket and my only chainring on the front. I believe that the chain may be too short and has stretched, causing the sprockets to slide off and creating this loud popping sound. Btw. all I'm still beginner in those subjects and probably make a lot of mistakes but I'm willing to learn anything related to bicycles and e-bikes
Here's a link to the bike specs: https://www.decathlon.co.uk/p/27-5-inch-mountain-bike-rockrider-st-530-mdb-black-yellow/_/R-p-341628
