Fox 36 ebike knock

[AusE]

Thought I had a loose headset but seems more like coming from air shaft side of fork, its only done 400k. Thoughts?

 

[brash]

Internal or external battery? Firstly check to see if your battery is loose in the holder/cradle. This is a common thing that people believe is CSU noise. Even take the battery out and try to replicate.

Next port of call, take note of Air spring pressure, slowly release air from Air Spring and undo air spring/spacer top cap with 32mm (off top of my head) chamferless socket/tool.

Inspect the air spring, sometimes the volume spacers can unclip and rattle in the air spring but this is very rare in my instance especially with the fox "clip" design. We see this common with the cheaper Rockshox forks though.

A CSU creak is a very distinguished "cracking" or creaking noise. Fox are well aware of the issue and will replace under warranty but from my experience the Ebike rated forks have had a good track record with CSU's, the normal 36's can't say the same.

 

[#lazy]

My mrz forks creak like an old mans knees ! Doing the loctite trick tonight , if still bad can warranty them !

 

[mxh]

I had the CSU creak on my Fox 36 Ebike forks - I also thought it was a loose headset to start with as does sound a bit like a rattle when going over rough ground. If it is the CSU you should be able to force the noise to happen when stationary - I took the bike back to the shop, demonstrated the creak and the shop got them changed under warranty with no issues.

 

[AusE]

Thanks for the replys but definitely not a creak but a knock cant really hear it when riding. I read somewhere about oil draining from the bushings and causing bushing slop so I turned the bike upside down manipulated the fork a few times put back up and knock gone, surely there cant be that much play in new forks.

 

[brash]

The old saying goes, Rockshox give you minimum oil, Fox give you none at all.

The amount of times I've dropped the lowers on a new bike and it been bone dry in there is too many to count.

Bushing tolerances have also a lot to be desired. Having them sized and replaced is always a good bet come first service. MTB suspension centre in Sydney are good for this service.

 

[DrStupid]

What is CSU? Something to do with the crown and the stem?

 

[#lazy]

Csu means crown steerer unit !

 

[AusE]

Cheers guys definitely not a csu creak, I'm pretty sure its bushing play when the oil drains to the bottom as it only seems to be there after bike has sat for a while. Time to crack them open for a look.

 

[redrhino]

I just got a YT Decoy 29 Pro and am noticing what sounds like the same issue with bushing play. You can hear it knocking and I can put my hand down around the legs at the seal where the uppers and lowers meet and feel movement. Bummer. I checked two other bikes with normal 2020 Fox 36 forks and they have no play like this.

 

[AusE]

Mine got sent for warranty ended up with new bushings installed

 

[redrhino]

Mine got sent for warranty ended up with new bushings installed

Good to hear, thanks. I'll contact fox after getting a few more rides in on the new bike.

 

[Uberpunk]

Hi, I have exactly the same bike ( Decoy Pro29 and exactly the problem with my Fox 36 Elite forks. They knock and you can feel it in the fork leg when you hold around the seal and rock the bike.

Wondering did you get this sorted ?

 

[AusE]

Hi, I have exactly the same bike ( Decoy Pro29 and exactly the problem with my Fox 36 Elite forks. They knock and you can feel it in the fork leg when you hold around the seal and rock the bike.

Wondering did you get this sorted ?

Yes mine got covered under warranty with new bushings, to check if its bushing play turn the bike upside down and pump the forks a few times this will push the oil between the stanchions and bushing. Turn back up the right way and check for play it should be gone until oil runs back down into lowers. Hope this helps

 

[redrhino]

YT directed me to the Fox warranty form on their website. They had me return it and fixed it under warranty. It took about 2 weeks here in the US when I did it.

 

[klevtik]

Had the same problem with fox 36 factory. Orbea sent me new 38 instead

 

[E-Bandit]

I have the same issue, after washing the bike I could feel the knock looked at everything and seems to be the fork, turned upside down and pumped the forks then picked bike back up and knock is gone.... is this normal or should I take back to 99bikes? Bike is 10months old.

 

[redrhino]

I have the same issue, after washing the bike I could feel the knock looked at everything and seems to be the fork, turned upside down and pumped the forks then picked bike back up and knock is gone.... is this normal or should I take back to 99bikes? Bike is 10months old.

When you turn it upside down oil moves around the bushings and takes up the space that causes the play. It will likely come back after a ride.

 

[E-Bandit]

When you turn it upside down oil moves around the bushings and takes up the space that causes the play. It will likely come back after a ride.

So I should take it to the shop for a warranty claim?

 

[redrhino]

If it comes back you could try that. YT had me warranty it directly with fox Mountain Bike Service RA Request | FOX

 

[E-Bandit]

Ok I’ll keep an eye on it,
Think that fox warranty is only for USA , I’m in Australia, does anyone know how to contact fox locally here?

 

[Mteam]

A friend of mine had this with his fox 36 ebike forks, we happened to just turn them upside down and cycle them a couple of times , and the knock went away, and hasnt come back since, that was about 300 miles ago.


My 36 ebike forks havent had the knock .

 

[E-Bandit]

A friend of mine had this with his fox 36 ebike forks, we happened to just turn them upside down and cycle them a couple of times , and the knock went away, and hasnt come back since, that was about 300 miles ago.


My 36 ebike forks havent had the knock .

Completed one ride and when I got home the knock is back... time to take it to the shop

 

[E-Bandit]

Completed one ride and when I got home the knock is back... time to take it to the shop

Went back to shop and they reckon it’s because it’s overdue on a service, I argued it wasn’t and there going to send to fox for inspection and see what happens

 

[E-Bandit]

Got my fork back yesterday and all covered under warranty, replaced the bushings , replaced lower bath oils , seals, foam rings and air side service. See if it doesn’t come back.