Bosch CX - clunking when pedaling

JuiceStainV&RStick

JuiceStainV&RStick

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Hey all, I'm getting some light clunking when pedaling - 1 to 2 clunks per revolution. Not normal MTB creaky sounds, seems to be coming from the motor area. I checked all bolts that are accessible and they're still torqued to spec. Ordered a cassette tool (BBT-18) to check the lockring, that should show up today.

Anyone seen this before? Thought I'd check in for known issues before I take it in for warranty evaluation.

Santa Cruz Bullit, CX gen 5, only 250 miles on it.


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RustyMTB said:
Does it clunk with the chain removed I.e. disconnected from the drive train? That will help rule out the cassette, mech, freehub, wheel, brakes etc.
Click to expand...
It needs a few meat watts to be applied to the pedals to do the clunking. Does it in my detuned Tour setting as well as in higher settings.

Makes no sound in the stand pedaling with chain pulled, but of course that doesn't engage the motor assist. I just swapped wheelsets 2 rides ago, does it the same on both. I also just did a brake bleed, did it before and after.

Re-checked all pivots, chainring bolts and headset - all tight. I'm 90% sure (never can be 100%) that it's coming from the motor area.
 
JuiceStainV&RStick said:
Hey all, I'm getting some light clunking when pedaling - 1 to 2 clunks per revolution.
Click to expand...

You'll want to check the lock ring that holds on the spider. It's notorious for coming loose. There's been debate on the forum regarding the proper torque and the proper thread treatment. Regardless of whose advice you choose to follow, you really need to check it. And since checking the spider involves removing the cranks, you'll be able to check those, as well. And since you're working on the cranks, check the pedals. There are also the four bolts that attach the chainring, but I've never seen them come loose on their own.

Spider, cranks, pedals. That's the best place to start.
 
Could put it in walk mode without the chain & that will engage the motor. Otherwise, if you're ruling out drive train & it's 250 miles in, dealer time. Let them find it.
 
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