Worn out Shimano XT 2x10 Chainring in 6 months?

TwoHeadsBrewing · Mar 27, 2013

As the title says, my big chainring on my Shimano M785 crankset is toast. I tried putting on a new chain yesterday and when standing in the big ring, it just slips off. It's not noticeably worn just looking at it, but it's definitely slipping on the chainring, not the cassette. I swapped the chain a little over 3 months ago, and at that time had no problems. I also find it odd that the small ring is fine: I can stand up and hammer it with no problem. It seems like the ring with less teeth and the one I use for the steep hills would wear out first.

I ride 2-3 times a week, and have never had a chainring wear out this fast. Is this a normal expected life span for the Shimano 2x10 stuff?

Just for reference I'm using a 26/38T (AK) version. The replacement big chainring is about $75.

jlmuncie · Mar 27, 2013

What do you mean it slips off? Pics?

TwoHeadsBrewing · Mar 27, 2013

You can't see it in a picture. It's when you stand and put a lot of power down on the pedals, the chain jumps a few teeth on the chainring. I've had it happen before on the cassette, but never the crank.

jlmuncie · Mar 27, 2013

FIDK, when I have a worn out ring I get massive chain suck. Never had a skipping chainring.

indyfab25 · Mar 29, 2013

Yup, same experience herewith the big thing wearing too fast. Awful.

dalboy · Mar 31, 2013

Yes I had the same thing. A replacement here is $160 odd, I ended up going for the 9 speed 36t big ring and I think its Ideal.

TwoHeadsBrewing · Apr 1, 2013

This is disappointing, especially for a somewhat expensive crankset. Guess I'll be replacing my chain more often, because the replacement rings were almost $100. I wonder if they went with a softer aluminum in order to drop weight. There are a few parts I don't mind being a bit heavier if that means they're stronger and last longer, and the crankset is one of them.

kcvpr · Apr 4, 2013

The strength of the aluminum would have nothing to do with the weight of the chainrings or crank. Other than having to design the chainrings or cranks to compensate for the diferences in strength. It has more to do with the heat treatment of the aluminum than anything, correct me if im wrong.

thomllama · Apr 1, 2013

I just had the same issue last yr, but it was a 6+ yr old Stylo crankset and the last 1 1/2 to 2 yrs I was doing an "experiment" to see how long a drive train would last.. Stock (4 yr old at the time) front rings, new-ish KMC 9xls chain and a sram 980 cassette.. the chain had worn thru a few actual bearing/pins so when I changed the chain and cassette the chain would just skip over the teeth on the front ring under power... kinda to be expected.

to last only 6 months even if you're a daily rider/racer it isn't good and honestly should be a warr issue...? thou I highly doubt Shimmy's gunna back it. :skep:

get a nice rugged after market (blackspire's are pretty tough) and forget Shimmy's stock units.

One Pivot · Apr 1, 2013

You should be able to use a 2x10 SLX ring, right?

The 9 speed XT rings have always been my go-to as I seem to trash every single other stock ring out there. Sucks to hear they're not holding up now!

TwoHeadsBrewing · Apr 3, 2013

Well it was definitely a worn out big ring that was causing the problem. I replaced both rings yesterday then went for a good long ride, and had zero problems. Still don't see how I toasted a big ring in 6 months with two chains. I always keep the chain well lubed and wipe it down every ride.

I just got the same rings as stock (26/38AK) for replacements, so we'll see if they hold up any better.

LyNx · Apr 4, 2013

What chain did you replace the stock with, very curious? I usually use CN7701/XTR (run 9spd) but found a deal on a KMC 9.9 chain and gave it a go because it was so cheap, biggest waste of time ever, waste of time chain, no where near the quality of Shimano, now resides on a loaner bike. If you want replacement chain rings that will last, buy Blackspire, my last set lasted well over 4 years and probably well over 6k miles.

thomllama · Apr 4, 2013

LyNx said:
)but found a deal on a KMC 9.9 chain and gave it a go because it was so cheap, biggest waste of time ever, waste of time chain, no where near the quality of Shimano, ....

you compare a top of the line Shimano against the bottom of the line KMC...? and to be honest.. the KMC is going to be stronger, honestly most cheapo chains are stronger, just heavy and not as "pretty" looking as they are usually just straight steel with no finish on them.

has it failed? or just that it didn't have a nice finished look the reason you don't like it? just so ya know, it is a decent chain.. far from the best, but it'll do the job and most likely wont break,.. it will rust if not cared for thou

I do agree with your blackspire comment! about the nicest. strongest rings I've dealt with.

TwoHeadsBrewing · Apr 4, 2013

I use a KMC X10SL, which I've never had a problem with. In fact, the only chains I've broken were Shimano...the KMC chains are a little heavier, but have never failed on me.

AntiNSA · Sep 23, 2013

I am so pissed off to. I only had 15k km on mine and I thought they would go at least 50k km. I had no idea they wore out. And now they try to force you to upgrade to a 10 speed set up, and they dont even make the 48t m-771 I was using anymore. I thought everything was so new I only had it like a year and a half. I thought xt was all about durability. Sucks copmpletely.

Worn out Shimano XT 2x10 Chainring in 6 months?

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