[A] Oval chain ring possibly worn out clutch

[Frosty]

Yoh! I've learnt something today.

 

How long has this clutch-type derailleur been around for? Asking for a friend.

 

No seriously, the reason I ask, is that after reading this thread, I checked my newly acquired, second-hand bike (2016 Anthem) and I see there's a clutch-type (SLX) derailleur. 

 

I've had the bike since June and have only done a handful of rides (I'm a roadie with a running problem), and was none the wiser. In fact, the first two rides were early morning coffee rides, and I never noticed the oval chain-ring until the first proper off-road ride.

[GrahamS2]

It is a friction based system. UNder normal use the clutch is preventing rapid movements of the cage whilst remaining free enough to allow the cage to articulate when changing gears.

With an oval you have 2 small rapid movements of the cage as it follows the rise and fall of the chainring. Its these little movements the clutch is designed to prevent. You're now adding increasing the number of cycles the unit is working through hence t wears faster. 

Yes it can be serviced.

But by then it already displays wear (its a friction based system so wear must happen)

More cycles more wear. Simple really

Not buying it, sorry. Have you seen how much a chain swings and bounces under normal mtb use? It's significant. And the entire point of the clutch is to minimise that movement, so it's engaged every time you hit a bump.

Edited August 28, 2019 by GrahamS2

[V18]

I keep on getting issues with my slx clutch and oval setup on my full sus. My bike doesn't pedal bob as much as the oval ring causes back and forth oscillations of the derailleur arm. The wear on the clutch only started becoming noticeable after I switched to oval rings. Even a new rear derailleur quickly fell victim. Luckily the serviceability helps a bit. Unfortunately it doesn't ever become good as new. Oval definitely doesn't love clutches or vice versa.

[bullet77]

I've run a XT 1x11 with oval ring from new, it's done 6000km+ and still works well.

What clutch wear issues can one check for?

What are the effects of a worn clutch?

[solty]

I recall seeing some footage where the TV camera zoomed in on Chris Froome's rear derailleur was bouncing around like crazy because of those square rings he uses. Road was dead flat.

[Reme Le Hane]

I've run a XT 1x11 with oval ring from new, it's done 6000km+ and still works well.

What clutch wear issues can one check for?

What are the effects of a worn clutch?

In my case in the 11t the chain was literally hanging on the chainstay. Lbs has service it but there is still a dead spot in the clutch, its alive but its a lot "older" than it should be.

[DieselnDust]

I recall seeing some footage where the TV camera zoomed in on Chris Froome's rear derailleur was bouncing around like crazy because of those square rings he uses. Road was dead flat.

 

 

Thank you!. The harmonics the ovals set up is where all that additional movement comes from.

Also when the derailleur isbouncing around due to bumps its mostly articulating around the mounting knuckle pivot.

The clutch is design to dampen forward swinging motion of the cage to assist with keeping the path the chain follows as long as possible. A lot of that movement is at the upper knuckle. The extra movements set up by the harmonics due to the ovals is over an above normal movements.

Absolute Black have a video where they show their chainrings have no effect. I have to laugh at it because the thy only demonstrate the zero effect by pedalling backwards  thereby not setting up the harmonics on the slack side of the drivechain. By pedalling backwards the pulley cage is under tension so the harmonics are not present. They also pedal so slowly....its a really funny video. 

[Steady Spin]

A year an a bit later and I’m curious if more people found this to be true?

 

Over the weekend I noticed that the recently installed 30t oval on my bike causes the chain to drag over chainstay protector and it’s busy eating it up. (never a problem with a round 30t)

 

I immediately thought about just replacing it with a 32t for extra clearance.

 

Google brought me here and I agree 100% on the clutch taking more strain with every rotation of the cranks. I don’t want to destroy the clutch on an XTR 12spd mech before its time.

[Puncture Kid]

A year an a bit later and I’m curious if more people found this to be true?

 

Over the weekend I noticed that the recently installed 30t oval on my bike causes the chain to drag over chainstay protector and it’s busy eating it up. (never a problem with a round 30t)

 

I immediately thought about just replacing it with a 32t for extra clearance.

 

Google brought me here and I agree 100% on the clutch taking more strain with every rotation of the cranks. I don’t want to destroy the clutch on an XTR 12spd mech before its time.

Shouldn't you be shortening the chain if you install smaller ring? The derailleur can only take up a limited amount of slack

[Steady Spin]

Shouldn't you be shortening the chain if you install smaller ring? The derailleur can only take up a limited amount of slack

 

Absolutely. Chain length should always match cassette and chainring installed. 

 

Shouldn't be applicable to the oval or problem that I'm having.