Bosch CX Gen 5 rattle

twisted_trails

twisted_trails

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Anyone else experiencing rattle going down on gen 5? Mine was quite silent in the begining, but after about 300km something started to rattle. I have hard time pin pointing exact location of the rattle, feels like it could be coming from higher up from downtube / battery area, but probably just sound bouncing inside the frame.

Sounds quite noticable in this vid -
I have SC Vala and actually got the bike because gen 5 was supposed to be silent 😅

Thanks!
 
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Thanks for the info! I checked headset couple of times so I really doubt it's that. Even if I drop the bike standing next to it it's quite silent. But it gets quite noticable at higher speeds and bigger hits. Feels a lot like rattle coming from gen 4 or ep8 which I tested both some time ago.
 
I'd check to see if the screws on the bottom of the down tube are tight. There are 4 of them that should have loctite on them (9nm) and if I remember correctly they hold the battery in the frame.
 
thank you, I'll check that, I suspect it could be the battery. This is my 3rd santa cruz bike and I never had cables ratttling inside the frame, so doubt it's that but I need to check how Vala has cables done
 
battery screws are super solid without anything moving. one thing I noticed today is Fox Performance 38 has some play when fully extended. I was told that should be normal and goes away once in the sag, so I kind of doubt that would cause the rattle troughout the frame
 
I had a creaking/rattling noise on my Bullit under pedaling and cornering loads. Sounded like it's coming from forks or headset. In the end, I tracked it to battery cover and solved with cleaning + 3M bitumen tape. Not really helpful as your Vala has a completely different system, but maybe check the plastic guards and covers for either loose fit or interference with frame/screws.
 
The Vala has internal cable routing. So, it's probably not likely that the cables are causing the noise. The other things you could put a wrench on just to narrow it down are the caliper bolts, rear chainstay pivots, shock mount bolts, and headset. It's always tricky on the carbon frames because the noise resonates through the frame, making it hard to determine where the actual noise is coming from.
 
The Vala was susceptible to some issues with the motor bushings. Did you checked them if they are all OK, torqued to spec?

I have a Mondraker Crafty with Bosch Gen 5, except some shimano pads rattle that was easy to fix, now the bike is dead silent.
 
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thanks everyone. I checked more or less everything troughout the bike. I'm taking it to the shop in couple of weeks to check motor etc...they couldn't provide earlier date. Meanwhile I'll check the fork - I noticed Fox 38 Perfomance has some play when fully extended, which might be causing the noise to echo trough the frame? Not sure if it's that but fork play seems a bit odd
 
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twisted_trails said:
thanks everyone. I checked more or less everything troughout the bike. I'm taking it to the shop in couple of weeks to check motor etc...they couldn't provide earlier date. Meanwhile I'll check the fork - I noticed Fox 38 Perfomance has some play when fully extended, which might be causing the noise to echo trough the frame? Not sure if it's that but fork play seems a bit odd
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If you feel play when holding front brake on and rocking the bike backwards and forwards then that could be play in the forks or more likely the headset bearing is loose, the latter of which can be caused by the top cap bolt not being tight enough. If this is the case the stem bolts will need to be loosened off before tightening the top cap bolt then re-tightened afterwards. Tighten the top cap bolt until the forks don't move freely (which means it's too tight) then back off the top cap bolt maybe 1/8 turn so that the forks (when held up in the air) just move freely.
 
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irie said:
If you feel play when holding front brake on and rocking the bike backwards and forwards then that could be play in the forks or more likely the headset bearing is loose, the latter of which can be caused by the top cap bolt not being tight enough. If this is the case the stem bolts will need to be loosened off before tightening the top cap bolt then re-tightened afterwards.
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thanks, very much doubt it's headset as I did all the checks on it, put it apart and together, tightened top cap then the stem... holding the brake + headset there is no play in the headset, but there is in the fork bushings. Here's a vid of fork play
 
Have watched the video again. Something is banging around like it's loose, and doesn't sound like motor. Might be the dropper post or motor bolts.
 
Hmmmm....I have the exact same issue. Brand new Bullit with a mystery rattle. Best guess is battery.

Will be investigating more this week and will update I'd I find anything.
 
In my case (2025 Bullit) it was just the plastic armour piece. Not screwed in properly from the factory. Backed it out, installed straight, tightened up and now quiet.

It's the small hex bolt by the motor mount bolt, but check all yours. There's a few.


1000046886.jpg
 
congrats you figured it out that quick! these were all good in my case. I dropped the fork today at fox service today and it needs bushings replaced. it actually had so much play I believe that was echoing trough the frame. will report once I get the fork fixed and go for a test ride
 
Redders473 said:
My vala has a rattle as well can't figure out where.
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Well so far I've had the aforementioned cover screws issue. They seem tight to the surface but have not pulled tight to the frame. Back out and retighten.

Also have had the rubber isolater on the motor mount bolt try to escape. If that's missing it might make noise. I took both bolts out, cleaned and lightly lubed and put back.
 
with fork serviced and new bushings, fork play is gone, but the rattle is still there. I checked the motor cover screws, tried to add additional tape on it temporarily to see if that fixes it but NOPE, same rattle.
If there's a bit of tolerance, I can try slighly repositioning it, but not sure if the cover should touch the frame or should I try to keep spacing so it's not bumping into the frame at any point?
one more suspect would be the dropper cable, looks like that goes straight into the seat tube and not visible by motor/battery, but didn't remove the post yet to look what's happening in there
 
twisted_trails said:
with fork serviced and new bushings, fork play is gone, but the rattle is still there. I checked the motor cover screws, tried to add additional tape on it temporarily to see if that fixes it but NOPE, same rattle.
If there's a bit of tolerance, I can try slighly repositioning it, but not sure if the cover should touch the frame or should I try to keep spacing so it's not bumping into the frame at any point?
one more suspect would be the dropper cable, looks like that goes straight into the seat tube and not visible by motor/battery, but didn't remove the post yet to look what's happening in there
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Any luck?
 
JankyMcJankface said:
Any luck?
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not yet. Same rattle as before. I also reinstalled dropper cable and made sure it's tight but same rattle continues. I took the bike to the shop today and we'll try to see if some foam around dropper cable helps. really seems like it can't be anything else than cables rattling inside the frame but will write it here if I find anything else.
 
Bike now has freshly greased and installed motor bolts and dropper cable wrapped in foam. But the rattle continues o_O

Atfter my ride yesterday I noticed one up dropper has quite some horizontal play when lowered. I know it should be a normal thing, but if it gets rowdy if could cause the noise to echo trough the frame. I'll try to check that on the next ride
 
twisted_trails said:
Bike now has freshly greased and installed motor bolts and dropper cable wrapped in foam. But the rattle continues o_O

Atfter my ride yesterday I noticed one up dropper has quite some horizontal play when lowered. I know it should be a normal thing, but if it gets rowdy if could cause the noise to echo trough the frame. I'll try to check that on the next ride
Click to expand...
Just out of curiosity, is your bike bone stock or have you "put the eyebrows on er" so to speak?
 
gbcoke said:
I think this thread subject needs to be changed to "VALA Rattle".
There are MANY gen5 motors out there and 0 report on rattle yet so it's just a bit misleading.
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I know, sorry, it just felt very much like classic motor rattle from shimano or previous gens bosches. Ultimately we'll probably get to "(insert bike part) rattle" title.
Johnny Smoke said:
Just out of curiosity, is your bike bone stock or have you "put the eyebrows on er" so to speak?
Click to expand...
completely stock S build
 
I have a trek gen5 and managed to pinpoint the rattle to the battery lock/release mechanism. It's very loose and rattles like hell. If the Vala has a smiliar one then this might be your culprit. It can be replaced witha n ABUS key, not sure if this will help so I'm just rolling with the rattle for now. It's not a big problem once you know what's rattling - at least in my case :D.
 
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