[A] Oval chain ring possibly worn out clutch

[Reme Le Hane]

So bikes in with the LBS for routine suspension service, but while ridding Saturday I noticed I had no tention on the chain in the 11t. They suspect and pre oval putchase the Internet had theorised a link between oval rings and extra wear which logically makes sense.

 

Pre race a few weeks back I had dropped to my 30t round and subsiquiently found my rides to be pretty ksk, burning out way faster, like getting full vitality points on a jeep track ride that had not earned me a single point in over a year.

 

Swapping back to the 32t oval made the world all happy again. A friend suggested it could be me having been more used too the power required on the larger ring, that I was sort spinning more maybe and that was zapping my energy, I dunno.

 

So derail ure is about a year old, say 3300km,ovals been on just under 4m for 1300 of those kms.

 

So not sure what's best going forward, would just getting a round 32t keep me ridding happy or is the oval really the secret and I just cary on risking eating derailure?

 

What's the wealth of experience around here.. . Shots

[Martin PJ]

What derailleur is it? I don't think the oval makes much difference to the derailleur. The total amount of chain in contact with the oval chain ring remains constant as the chain ring is pedalled. So the derailleur should not feel much difference between round and oval.

[Barry]

Service the cluch new grease and adjust tension screw in the cluch simple contraption would take a lot to wear out the cluch

[Reme Le Hane]

Service the cluch new grease and adjust tension screw in the cluch simple contraption would take a lot to wear out the cluch

LBS is going to tlc, they just warning it may not live much longer as its pretty stuffed apparently. So probably by years end a new ones going on.

What derailleur is it? I don't think the oval makes much difference to the derailleur. The total amount of chain in contact with the oval chain ring remains constant as the chain ring is pedalled. So the derailleur should not feel much difference between round and oval.

Pretty sure it's a Shimano XT.

 

It would, how much I am not sure, but generally on the long side you have the equivalent of a 30t and shirt side a 34t. On a round ring your pedal stroke isn't really activating the clutch, but as far as I understand, on every revolution when your chains on the short side you are engading the clutch.

 

The is apparently marginally more tention in the chain because of the change.

[DieselnDust]

ovals will and do wear the Shimano Derailleur clutches more quickly. Its a known issue. It has more to do with the design of their clutch no liking the constant movement.

The SRAM derailleur seems to care far less

[Martin PJ]

Doesn't matter where you measure the chainring, if you take from one side to exactly opposite the other side there is the same number of teeth. The chain only contacts about half the teeth in the chainring at any one time. I have a 34 oval chainring and just checked now, the derailleur (SLX 10 speed clutch) does not move much when you pedal.

[Martin PJ]

 

Check this video out. My derailleur moves slightly like the XT in the video. The guy in the video reckons this causes problems with the clutch derailleur in the long term. Guess it is possible to service the Shimano clutch derailleur and this should be done after a year or two.

[Reme Le Hane]

ovals will and do wear the Shimano Derailleur clutches more quickly. Its a known issue. It has more to do with the design of their clutch no liking the constant movement.

The SRAM derailleur seems to care far less

Then my thinking is, if I can at least keep the derail ure running much closer to my cassettes death date, which chain 2 has just hit 0.75 so should also die around years end, then grab a sram nx upgrade kit and live happily on with my oval. Long run that seems the most cost effive as a new cassette, derail ure and chain would run a little over 3k and the upgrade kits just over 4.

[Martin PJ]

In the youtube video the Shimano clutch derailleur is a bit stiffer than the SRAM, which could be why it is affected more by the oval movement. The extra stiffness may be an advantage or disadvantage, it's why I like Shimano. I use oval and round chainrings, I don't think the chainring shape makes much difference. At the moment I am using oval because it's what I have.

[NotSoBigBen]

 

Check this video out. My derailleur moves slightly like the XT in the video. The guy in the video reckons this causes problems with the clutch derailleur in the long term. Guess it is possible to service the Shimano clutch derailleur and this should be done after a year or two.

I wonder how 'long term' would be defined?

[Martin PJ]

Long term would be a year, I guess. I haven't really noticed any problems with my setup after 18 months. Just that the clutch is very stiff. Has always been like that. Gear changes are more difficult with the clutch on.

[DieselnDust]

I have seen this issue with every Shimano derailleur fitted with a clutch and where an oval chainring is used. My sample size isn't as big as an lbs but I don't see the issue with drive trains using round rings.

[Me rida my bicycle]

Shimano has a small clip inside which the switch outside engages, that is the thing to break. I have seen a couple of those let go.

I am on my second chain and oval and my Sram derailleur is still perfect, the Shimano XT on the other bike needs TLC every now and then and setting. I can't remember when last I have needed to do anything to the Sram except for the obvious cleaning every now and then.

[Martin PJ]

I have seen this issue with every Shimano derailleur fitted with a clutch and where an oval chainring is used. My sample size isn't as big as an lbs but I don't see the issue with drive trains using round rings.

Another reason to use a round chainring. I really like Shimano clutch after battling with a few very muddy rides and getting chain suck.

[porqui]

As far as I can figure it should make no difference oval or round - there is so much movement there anyway. But servicing the clutch once in a while would help a lot. That grease in the clutch would make all the difference.

Edited August 28, 2019 by porqui

[GrahamS2]

I have seen this issue with every Shimano derailleur fitted with a clutch and where an oval chainring is used. My sample size isn't as big as an lbs but I don't see the issue with drive trains using round rings.

It's not made of glass. Surely riding a mtb in it's intended environment results in chain bounce and will induce constant movement in the rear derailleur? They're designed for pretty hard use on mtb's.

 

I know many, many riders who use oval rings and have never heard of a clutch wearing out. Pretty much all ride Shimano XT or XTR.