Renthal Twinring wear?

I just changed out my Ironman 49 tooth sprocket to a 50 tooth Twinring sprocket about 2 rides ago. Chain is a DID 520VM with no noticeable stretch(has about 25 hrs on it). I did not replace the chain at this time because there was no stretch from the chain. My Twinring sprocket looks horrible after around 2 hours and 2 rides on it. The chain has worn grooves into the steel part and the back sides of the teeth are starting to push outward. Sort of like peening. Everything is aligned. I find it hard to believe that it can be this bad this quickly. It is wearing worse than a cheap aluminum sprocket.

My ironman sprocket showed no noticeable wear and it has been on there for about 25 hours. Bike has 27.6 hrs on it. Stock chain and sprockets were replaced right after break in.


The chain can be measured for "stretch" easily enough. Using a 6" vernier caliper, set it at 5.8", insert it between the chain rollers, and step down on the lower run of chain to bring the top run taut. Measure the distance between the rollers. A new 520 will measure 5.85", and it should not exceed 6". I replace them as they get to 5.95". Be sure to measure several different sections.

If you haven't got a caliper, have someone help you measure center to center over 31 pins. New, that should be 18.75", at the 2% limit, that's 19.125" (19 1/8)

If the teeth are pulling out, and not forward, it may be a rear wheel alignment issue.

I will check that when I get back home. The chain is leaving a notch on the lower back side of the teeth and it is also pushing outwards on the front and back of the sprocket evenly. Almost like the chain is acting like a hammer hitting soft metal would do.

Just so I am clear also, back side of the teeth is the part the chain pulls on when riding.....

Just so I am clear also, back side of the teeth is the part the chain pulls on when riding.....

"Drive side" :excuseme: The other face is the "coast side".

Either way, it sounds like something I'd be less than impressed with.

X2 on the chain, it should be replaced at the same time since even a "slightly" worn chain can cause a new sprocket to go very quickly.

I put one on my 450 with a new chain an after 5 rides it show signs of wear already , not to impressed with the sprocket. The ragina chain is haggin in there. are some pics and measurements...

By the caliper method, I was getting readings of 5.88".

By measuring from the center of pins over a 31 pin span, I was getting 18.78" or 18 25/32". The chain has only stretched a 1/32 of an inch over the 31 pin span which would relate to my only having to adjust the chain 1 time since new....






Judging by the material rollover ("mushrooming") at the edges of the worn area, the metal looks unserviceably soft to me.

I agree...and this is only after approx. 2 hours of use. I am awaiting a callback from Renthal...

WOW I wouldn't be impressed with that at all...

mine did the same thing let me know what you find out.

I guess Renthal has a very small customer service dept. One person. I left a message yesterday mid-morning an tried numerous times throughout the day to get him. It was always his voicemail. Hopefully will hear back on Monday.

opinion.....stay with Ironman Sprockets

when i bought my 450 the previous owner had put a new regina rx3 chain and new sprockets on (twinring)... i got it with 0 hrs on them and i have maybe 5hrs on now and the rear has the same type of wear..but a little worse "rollover" on the side than yours...i absolutely would not purchase that sprocket and would advise any of my friends against it!

When I bought my first '06 3 1/2 years ago, I immediately replaced the stock chain with a Regina ORN6. That chain and the stock sprockets lasted 2 years. I replaced it with another ORN6, a Pro Taper front, and a Tag aluminum rear, and it's still in great shape. To be fair, I have to point out that the bike did have an 8 month break while my son went through boot camp and MOS school, being ridden only twice in that time, but in the nearly a year that it has on that setup, the wear on the sprocket is minimal, and nothing at all like the Twinring shown.

My own bike, had two rides on the stock stuff when I bought it in September of '07. I replaced the chain at that time, again with an ORN6, and that chain has only now reached the point where I need to replace it. (It's only stretched about 1%, but it's starting to stiffen a bit) I could actually reuse the stock Sunstar rear for a while, but I don't plan to.

Unless you have seriously mis-measured that rear chain, there is absolutely no justification for any steel chain ring, or even an aluminum one, to wear like that so quickly.

Just got off the phone with Brad in customer service. I got his e-mail and just fired off the pictures to him. I asked him what the process for this was and he said they would more than likely be sending me a RMA tag to send it back to them so they can test the hardness of it.

looks soft to me too. I would try to get a refund and get something else. i did what grey said too on my 07 before even riding changed out the stock chain and replaced with o-ring and I am still running stock sprockets with quite a few good rides on it, and my cheap sunstar looks better than that.

I use Twinring on my race bike and regular JT steel sprockets in my practice bike. The quality of the steel in the Renthal is not as good as in the JT. It starts to wear very soon, even in a few hours, as you posted, but then remains like that for a long time. I always get more time from other steel sprockets, but I noticed the twinring wears faster at first then it stabilizes.

opinion.....stay with Ironman Sprockets

agree....been using them since '05...:excuseme:

We have never had good luck with ANY of Renthal's sprockets - PERIOD! Kind of funny how their bars tend to bend under half the force of Pro Tapers or Tag Metal bars and are generally also more expensive. I have stopped buying their products and have come to the conclusion that just because they manage to get their name on just about every swingarm sticker known to mankind, doesn't mean they make a good product.

Companies that don't spend millions on advertising tend to have more money to put into manufacturing better products.

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