Renthal Twinring wear?

Looking at post 7, the chain is not worn enough to create the wear shown in the picture. The spec for a new 520 chain measured between 11 rollers is 5.85", and he had 5.88", which is barely 0.5% longer than specification. Yamaha's wear tolerance is 2% (5.97"), and I use 1.5% (5.93") as my personal limit.

The wear shown is not so much "wear" as it is peened, as if the metal had been to soft and yielded under pressure. Frankly, that isn't excusable, given that even my OEM Sunstar sprockets did't do that.

Finding fault where it lies is not bashing.

my OEM Sunstar sprockets did't do that.

Neither do aluminum sprockets with good chains. That's why his chain wear is questionable regardless of the photos.

I even rode a $17 RMA sprocket with a slightly used chain and didn't have any wear like that.

Neither do aluminum sprockets with good chains. That's why his chain wear is questionable regardless of the photos.

OEM Sunstar YZ sprockets are aluminum, heat treated, but not hardened. That was my point.

I know the OP well enough to trust that he can properly measure a chain, and I know enough to know that the wear in the photo is abnormal for a steel sprocket, and that a chain at 0.5% over length wasn't to blame.

Renthal did send me a new replacement Twinring after some time. They never did say whether it was a defective sprocket or something else. I was happy with the customer service I received but I gave the replacement Twinring away.

I have no issues with the Ironman sprockets and I have 85 hrs on the one on my 2007 bike and 20 hrs on the one on my 2010 bike. They show almost no wear.

I use the twinring with the renthal gold chain for 3 years on 2 450s. Never had that kind of wear on either. But I NEVER mix used and new parts.

I have twinrings on 3 of my bikes and haven't had any problems. 2 of the bikes have lots of time on them.

But the sprocket does look like the metal is soft.

Maybe they've improved them in the last few years.

Maybe the one he had was a real live defect that bypassed the hardening stage...hmm?

Thanks for that post. I was going to buy one of these sprockets, not now!

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