[Rc 44]

I have a 2021 Trek Slash 7. I have been annoyed with the sometines horrendous chain slap the bike makes. I tried completely covering up the seat and chain stays with foam and velcro to no avail. I then decided to record the chain movement on hard hits and noticed that as the derailleur extends from the impact, a wave travels throughout the lower part of the chain and eventually whips towards the chainring making a loud snapping sound.

The derailleur on the bike is a NX eagle with the type 3 roller bearing clutch, which isn't adjustable and many also report that it's weak. Since I can't increase the derailleur tension, I thought about putting a lower chain pulley close to the chainring to prevent the wave from propagating towards it.

Have any of you experienced a similar issue? Any advice would be greatly appreciated.

Slow-mo video: IMG-0967.mp4

 

[Taroroot]

Earbuds? Louder freehub? Trail chicken? SS?Belt drive? One of those DH chain guides with guides on top & bottom?

 

[noapathy]

Go get a 1996 Giant Iguana. Ride it a while and get back to us.

 

[Abunchahicks]

Is your chain too long?


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[teK--]

Swap for a Shimano derailleur.

 

[slapheadmofo]

Go get a 1996 Giant Iguana. Ride it a while and get back to us.

I'll see your Iguana and raise you a 2002 Intense M1.
Sounded like somebody threw a drum kit off the chairlift. LOL

Looking at the video, 2 things:

The chain looks long
The clutch doesn't seem to be working

 

[Harold]

in the smallest cog on the cassette, the derailleur is going to be at its least effective at controlling chain slap. you need a bit of tension on the derailleur spring for it to work its best.

This is a great example of a situation where a lower chain guide can help, as well.

 

[Rc 44]

I'll see your Iguana and raise you a 2002 Intense M1.
Sounded like somebody threw a drum kit off the chairlift. LOL

Looking at the video, 2 things:

The chain looks long
The clutch doesn't seem to be working

Yes indeed, the Sram Type 3 clutch has been known for being particularly weak compared to shimano clutches. Since it isn't adjustable I can't do much on that regard.

I'll try shortening the chain before installing any chain guides.

 

[Rc 44]

in the smallest cog on the cassette, the derailleur is going to be at its least effective at controlling chain slap. you need a bit of tension on the derailleur spring for it to work its best.

This is a great example of a situation where a lower chain guide can help, as well.

About the derailleur tension, I could increase it slightly by shortening the chain by a small amount, but I'm not sure if it'll be enough.

If that doesn't work I'll probably consider a full chain guide.

Anyways, thanks for the help!

 

[slapheadmofo]

Yes indeed, the Sram Type 3 clutch has been known for being particularly weak compared to shimano clutches. Since it isn't adjustable I can't do much on that regard.

I'll try shortening the chain before installing any chain guides.

Just make sure you leave enough slack for suspension action when in the biggest cog.
Otherwise your chain might shorten itself on a big hit.

 

[slapheadmofo]

About the derailleur tension, I could increase it slightly by shortening the chain by a small amount, but I'm not sure if it'll be enough.

If that doesn't work I'll probably consider a full chain guide.

Anyways, thanks for the help!

I wonder if it might not be better to swap out the derailleur to something with a clutch that works.