Bosch CX Gen 5 rattle

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.

oh wow, thanks that's good info to have. Is that accesible by simply removing the motor cover? are you refering to Abus brand key? I'm confused 😅

//edit nevermind, I see bikes with removal batteries have those. mine doesn't :LOL:
 
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oh wow, thanks that's good info to have. Is that accesible by simply removing the motor cover? are you refering to Abus brand key? I'm confused 😅

//edit nevermind, I see bikes with removal batteries have those. mine doesn't :LOL:

This is the default mechanism on my Rail. It's very loose and was loose from day one. I can access it once I remove the battery, but can't find details on how to replace it - probably something available to Bosch service centers.

1749044649849.png


It uses a 6mm allen key to unlock and release the battery. I belive this mechanism can be replaced with and ABUS lock:

If this would fix the rattle I'd probaly go for it.
 
I bumped into a chap last weekend. He was listing all the problems he's had with his Vala.

He said some Valas were shipped with the wrong size motor bushing. It's a known issue.
 
This is the default mechanism on my Rail. It's very loose and was loose from day one. I can access it once I remove the battery, but can't find details on how to replace it - probably something available to Bosch service centers.

View attachment 161913

It uses a 6mm allen key to unlock and release the battery. I belive this mechanism can be replaced with and ABUS lock:

If this would fix the rattle I'd probaly go for it.
I have the Abus lock as standard on my Cube and it doesn’t rattle. Doesn’t mean that all of them don’t rattle.
Can you not put some tape inside the latch cavity to cushion the rattle?
 
I have the Abus lock as standard on my Cube and it doesn’t rattle. Doesn’t mean that all of them don’t rattle.
Can you not put some tape inside the latch cavity to cushion the rattle?
I eyeballed the whole thing briefly and didn't try to disassemble it yet. Your suggestion would be a cost-effective fix, hope it will be possible.
 
A traduire en Anglais svp

Mon Vala xo axs a 1100kms aujourd'hui, Jai eu le même bruit que toi ... je suis même allez jusqu'à remplacer le jeu de direction, sans aucun effet, vérifie les vis du port de charge ( desserrer sur le mien ).
Mais le souci principal venait de la Fox 38 qui claquais dans les rebonds ( elle arrivait en butée supérieur rapidement). j'ai mis un SAG a 25% au lieu de 30% et le problème a disparu.
 
I bumped into a chap last weekend. He was listing all the problems he's had with his Vala.

He said some Valas were shipped with the wrong size motor bushing. It's a known issue.
that is probably same issue people had where bushings were falling out? I think SC fixed that and my bike doesn't seem to have that issue, unless wrong size bushings is a different problem

A traduire en Anglais svp

Mon Vala xo axs a 1100kms aujourd'hui, Jai eu le même bruit que toi ... je suis même allez jusqu'à remplacer le jeu de direction, sans aucun effet, vérifie les vis du port de charge ( desserrer sur le mien ).
Mais le souci principal venait de la Fox 38 qui claquais dans les rebonds ( elle arrivait en butée supérieur rapidement). j'ai mis un SAG a 25% au lieu de 30% et le problème a disparu.

interesting, since I replaced fork bushings it feels like my rattle mainly comes from back wheel hitting the ground and the front rattle is gone. charge port also feels tight without play
 
I think I found the cause of the rattle on mine. Took the dropper apart and noticed bushings are all chewed up and cartridge has visible dents on it from it hitting insides of the post. I guess it got loose after first 100-200km. I'm still waiting for response from OneUp

Screenshot 2025-06-13 091329.jpg Screenshot 2025-06-13 091348.jpg
 
I think I found the cause of the rattle on mine. Took the dropper apart and noticed bushings are all chewed up and cartridge has visible dents on it from it hitting insides of the post. I guess it got loose after first 100-200km. I'm still waiting for response from OneUp
Few months ago serviced my OneUp dropper with the new service kit after 4,000 miles (naughty, I know 😏).

The bushings were of course worn but nothing like as ugly as yours. Will be interested to hear what OneUp says ...
 
Interesting. My Vala started rattling a bit too, but I haven't dug into it. Subscribed.
 
I believe I had a few sources of rattle, but the one that remains seems to be related to the clutch mechanism in the drive unit. I notice it most on technical climbs where there's a lot of transition between pedal strokes and body english - the motor "spinning down" has somewhat of a rattle character. I also notice it descending when slower speed footwork is involved and am pretty sure it's the same noise / play in the system that I'm hearing.

Does this description ring true for others? I don't recall really noticing the sounds at first, but it could be that as I'm noticing it more now that I've settled into the character of the bike.
 
My gen 5 cube motor is starting to rattle like a gen 4 now. Annoying as it was silent when new. Done just under 850 miles.
 
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.
I second that! I had the same rattle going down hill on my Vala. Checked everything, and in the end, even feeling tight, the headset was where the sound and rattle was coming from. Solved that with tightening a little more.
Now dealing with bushing issue. :-(
 
hi mate, did this solve your rattle?
in short, No :(
Today I went for a test ride with completely removed dropper cable and standard seat post installed, rattle is the same. Feels like it's definitely coming from back or mid end when back wheel hits the ground.

Regarding OneUp post, I rebuilt it with new parts, but rattle stayed the same. OneUp also sent me new thicker pins, but I don't see point in changing those as it doesn't seem to be a dropper issue.

I also reached out to Santa Cruz and they are saying they have no feedback on frame related noise and are not aware of it. They mentioned noise sounds like it could be coming from Fox Float X shimstack design. I checked with Fox service and they're saying noise should change by changing rebound settings if it's coming from the shock. Playing with that without noticable difference with the noise. I also didn't take it for a service yet. Curious if anyone had that issue with their shock.

Otherwise I'm running out of ideas but suspect it might actually be coming from motor or battery. But I already checked that area and had motor bolts checked, regreased and reinstalled by the shop.

I also have Fidlock bottle which sometimes rattle but noise is the same or at least similar without it.

Clueless but I have hard time believing my bike is theonly Vala with that issue.

I waited for years for a bike that doesn't rattle going downhill.

Help.
 
in short, No :(
Today I went for a test ride with completely removed dropper cable and standard seat post installed, rattle is the same. Feels like it's definitely coming from back or mid end when back wheel hits the ground.

Regarding OneUp post, I rebuilt it with new parts, but rattle stayed the same. OneUp also sent me new thicker pins, but I don't see point in changing those as it doesn't seem to be a dropper issue.

I also reached out to Santa Cruz and they are saying they have no feedback on frame related noise and are not aware of it. They mentioned noise sounds like it could be coming from Fox Float X shimstack design. I checked with Fox service and they're saying noise should change by changing rebound settings if it's coming from the shock. Playing with that without noticable difference with the noise. I also didn't take it for a service yet. Curious if anyone had that issue with their shock.

Otherwise I'm running out of ideas but suspect it might actually be coming from motor or battery. But I already checked that area and had motor bolts checked, regreased and reinstalled by the shop.

I also have Fidlock bottle which sometimes rattle but noise is the same or at least similar without it.

Clueless but I have hard time believing my bike is theonly Vala with that issue.

I waited for years for a bike that doesn't rattle going downhill.

Help.
i’m same mate, got a bullit that’s 2 weeks old and have a bad noise when hammering down something fast and rough, can’t figure for the life in me what it is. So annoying
 
i’m same mate, got a bullit that’s 2 weeks old and have a bad noise when hammering down something fast and rough, can’t figure for the life in me what it is. So annoying
sounds like another e-santa cruz with rattle, might be something with their frames, internal cables etc... same on mine, mostly very loud on fast rough sections
 
Same as my gen 5 cube. Mines louder than a gen 4 Bosch on roots and rough stuff.
 
Is it possible for gen5 motor to rattle at all considering how it's made?

SC support replied with "A rattling from the motor is very unlikely and we haven't heard of any, so far."

Did anyone managed to get one replaced under warraty because of the rattle?
 
sounds like another e-santa cruz with rattle, might be something with their frames, internal cables etc... same on mine, mostly very loud on fast rough sections
yeah same here mate, sounds like it’s falling apart haha. So annoying because apart from that i love the bike, hopefully i’ll get used to it
 
I don't think it's something to get used to, more like something to fix. Especially with brand like Santa Cruz, but maybe I'm just optimistic enough there 's a sollution :)
 
I don't think it's something to get used to, more like something to fix. Especially with brand like Santa Cruz, but maybe I'm just optimistic enough there 's a sollution :)
it’s weird how some people it effects and others not, but yeah one of my main reasons for getting this bike was due to it being ‘silent’ hahaha!
 
did this test with the shock today, doesn't quite sound right and could be the cause for the rattle, need to check with local fox service

 
Mám Trek gen5 a podařilo se mi přesně určit příčinu chrastítka v mechanismu zámku/uvolnění baterie. Je velmi volný a chrastí jako čert. Pokud má Vala podobný, pak by to mohl být viník. Dá se nahradit klíčem ABUS, nejsem si jistý, jestli to pomůže, takže prozatím s chrastítkem nehraji. Není to velký problém, když víte, co chrastí - alespoň v mém případě :D.
Yes, my Trak Rail+ has same problem, my solution is on picture. I contacted my dealer to see if an Abus lock would solve the problem. I waiting for answer

20250804_174054.jpg
 
Is it possible for gen5 motor to rattle at all considering how it's made?

SC support replied with "A rattling from the motor is very unlikely and we haven't heard of any, so far."
SC told me back in the day they hadn't heard of the Fazua motors making weird noises, so take this with a grain of salt.

I'm convinced the "rattles" on my Vala motor are coming from small ratchet-like movements at the cranks. I find it fairly easy to reproduce when ratcheting quickly on a climb, and hear it normally on climbs with tech in them. In chunky descents where there's repeated small movements at the cranks it makes sense to me to be hearing the same sounds. I'll get a video of it to share here the next time I remember to take my action cam out.
 
Shock fully serviced with some internals changed, rattle stayed exactly the same 😕
I experienced the same annoying rattle on my bike, which turned out to be caused by the headset bearing. I don’t have the VALA, but this might help you solve your problem.
 
SC told me back in the day they hadn't heard of the Fazua motors making weird noises, so take this with a grain of salt.

I'm convinced the "rattles" on my Vala motor are coming from small ratchet-like movements at the cranks. I find it fairly easy to reproduce when ratcheting quickly on a climb, and hear it normally on climbs with tech in them. In chunky descents where there's repeated small movements at the cranks it makes sense to me to be hearing the same sounds. I'll get a video of it to share here the next time I remember to take my action cam out.
this sounds interesting, but I'm not sure if its that, as my bike was silent first 300km. I did try actually pedaling trough some rough downhill sections and rattle seemed quiet(er) but hard to tell that as pedaling over roots is tricky 😅 There a linked vid in my previous post now so you can clearly hear the rattle.
I experienced the same annoying rattle on my bike, which turned out to be caused by the headset bearing. I don’t have the VALA, but this might help you solve your problem.
thanks, I checked headset multiple times along with fork serviced but didn't help. might check again I guess
 
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