Chasing various noises on my Altitude A50

mildbill

New Member
May 1, 2024
4
4
Big Slabby, CA
5 months on an Altitude A50 - (3 months sat out with a calf / knee injury) Riding 2 - 5k ft most every day I wasn't injured. I have 2 noise-related issues driving me crazy, anyone with advice / experience?

Issue 1: something in my drivetrain is making a soft "thunk" when under partial load, at semi-regular intevals.
- Climbing a moderate hill on boost level 3 or 4 within the suggested cadence range but not pedalling as hard as I can - every 6 to 12 pedal strokes there is a brief "thunk" or "tap"
- It does not lead to a violent drivetrain skip like when a chain jumps on teeth
- It does not feel associated any kind of side to side displacement like a smoked bottom bracket or main pivot axle would
- It is not frequent enough / at regular enough intervals to be the chain's magic link ticking through one of the pulleys - but maybe there is a relationship between cadence / gear selection - still collecting data on that one
- It seems like it might go away when I am applying max torque (rare scenario where I am standing / pedalling)
- It does not seem present at lower torque levels
- There doesn't seem to be play in the BB

Issue 2:
- TACKTACKTACK coming from motor / battery area when descending - when I remove the bolt holding the battery in place I can sort of replicate the sound. Removing all the plastic covers and manipulating every component there doesn't seem to be anything loose /rattling around in the motor area.
 

mildbill

New Member
May 1, 2024
4
4
Big Slabby, CA
Issue 1 update: It appears the culprit was chain stretch - new chain (which required a new cassette) solved this.
Issue 2 update: reading other forums it sounds like I need to try the "soft side of velcro tape" trick
 

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