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  1. #1
    shh. don't tell the wife
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    Chronic broken chains

    I'm at my wit's end with broken chains on my DT. Its an '09 running a double up front via an e-type FD and an XT/ XTR combo.

    The last broken chain was on a rather new'ish XTR/Dura Ace chain running a KMC link. The chain gave way on a factory pin and sheared my derailleur in 2 below the hanger. At the time I was in the granny pedalling up a fire road (seated, no gear change).

    My rear drop outs are square (as near as I can tell) so things should be in line right. Any help would be great.

    tia.
    All you need is love... but Scotch'll do in a pinch.

  2. #2
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    Reputation: One_Speed's Avatar
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    Get a sram chain. You will save $$ and not be replacing chains. I do not get as much time out of a shimano chain.

    Purchased one for my dt and it lasted maybe 4 months. Chainrings lasted 6 months (Riding 5-6 times a week)

    I think the double with cross chaining, along with heavy bike wears em out. Using a sram road chain currently it is holding up longer than the shimano. (I got a bunch of em on sale years ago)

    I also hear kmc chains are excellent. Never used em on a mtb yet.

  3. #3
    shh. don't tell the wife
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    After a year+ of SRAM I can say SRAM isn't any better for me.
    All you need is love... but Scotch'll do in a pinch.

  4. #4
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    Quote Originally Posted by jitenshakun
    After a year+ of SRAM I can say SRAM isn't any better for me.
    hmm, Do you use lube?

  5. #5
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    Try the SRAM Cross Step chain. It's the strongest version of all the chains they make.

    I'd also make sure some of the basics are taken care and some other ideas:

    - No mismatches in the drive-train unless specifically supported (i.e. 8 speed & 9 speed parts mixed together)

    - Chain is well lubed

    - Cassette isn't worn-down

    - You aren't removing links and setting them back into the chain often or at all

    - Are you doing a lot of shifting while going uphill or when the chain is under a lot of load?

    - Take a look at what gear combo you are usually riding in on the chain. Is it a pretty straight line from the crank to cassette or are you angling it between high and low gears? That can weaken the chain.

    - Double-check to make sure the derailleurs are tuned correctly of if you are in doubt maybe have your LBS inspect it

    - If you want to get really anal about lubing the chain, either with a new chain or one you've full cleaned and degreased, you can soak it in paraffin or a thicker lube. It get's into all the joints and crevices and really keeps the dirt out. There are a few folks that swear by this technique. It's just a lot of work.

  6. #6
    MC MasterShake
    Reputation: woodyak's Avatar
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    There has got to be something funky going on. I haven't had the best luck with Shimano or SRAM chains but I've never had an epidemic of chain snapping. In fact I don't think I've ever snapped a chain on my DT in the 2 years I've owned it. I'd take a strong look at your chainrings and cassette. I'd like for bent teeth, burrs, spacing between teeth, defects or anything that would twist or improperly torque your chain.
    ]
    btw,
    I've had good luck with KMC chains but I can't find a cassette that I don't bend the rings on.
    Come stay and play at da Kingdom Trails! - http://www.homeaway.com/vacation-rental/p3486813

  7. #7
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    Sounds weird

    Is it possible your B-tension isnt set correctly and the derailluer is making contact with the cog under load and compressed suspension? I had this happen on my 2010 EG, I adjusted everything perfectly on the stand then went out and rode it, I was in the large cog and hit a bump pedalling and the cage caught the cog and snapped the der hanger, der, and chain. It seems that the derailuer moves closer to the cogs under suspension compression. I used to snap SRAM chains all the time so I switched to XT, however I have a 990 on the new EG and its holding up well but I clean it and lube it after every ride with a wax based lube.

  8. #8
    shh. don't tell the wife
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    Thank you for the feedback.

    A few more details about my set up:
    - I keep my chain clean and lube it prior to every ride.
    - In terms of set up its all Shimano, all 9 speed and all the same age.
    - The derailleurs have been set up by trusted LBSs.
    - I can also say I'm not running "forbidden" gears. i.e. no 42-34 combos.
    - I've only re-linked with power type links and as I stated this last break was in an untouched section of chain.
    - In general my chain stays on the bike.

    Next steps:
    I'm going to have a very close look at the cassette and check the B-tension on the derailleur.
    All you need is love... but Scotch'll do in a pinch.

  9. #9
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    I think it's safe to say your problem isn't with the chains. Something else is grossly out of whack somewhere. I've run some very worn out, hammered, drive trains, and they'll tolerate a lot of slop, missing teeth, etc, and still 'work'. I know they're done when the chain starts skipping across teeth or jumping off cogs, but they don't break on me like yours are.

    edit to add: I ride all the time in the 32 up front.

  10. #10
    Chillaxin 'n Chilcotin!
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    Maybe it's time for a hamstring/quadracept reduction surgery...

  11. #11
    shh. don't tell the wife
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    Quote Originally Posted by kristian
    Maybe it's time for a hamstring/quadracept reduction surgery...
    I sort of tried that earlier in the season

    I'm also going to see if a friend has a chain alignment tool I can borrow.
    All you need is love... but Scotch'll do in a pinch.

  12. #12
    What the ----?
    Reputation: Rich from CT's Avatar
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    Yea ease up Hercules & stop pedaling so dam hard.

  13. #13
    shh. don't tell the wife
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    I've been working on my style on technical uphills but in this case I was "egg beater" pedalling on the road, which is as smooth as I get.

    For reference I stand and hammer on my road bike like there's no tomorrow and have only ever broken a very worn chain once.
    Last edited by jitenshakun; 06-28-2010 at 01:27 PM.
    All you need is love... but Scotch'll do in a pinch.

  14. #14
    ಠ_ಠ
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    I've heard KMC chains are the way to go for guys who break a lot of chains.

  15. #15
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    in my experience, that Sachs/Sram chains are the most durable.
    I like the 991 cross step, the pins are peened in four places instead of two. Very strong and pretty wear resistant.

  16. #16
    Perpetual Hack
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    Just snapped a 971 on my new Delirium last night. It did have a couple hundred miles on it...
    Replaced with another 971 from the LBS at a price almost the same as a KMC X9-SL ( 45 from Jenson, paid 40 for the 971 but I gotta ride.)

    Thinking about getting two X9-SL and rotating them.

    michael

  17. #17
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    I still don't understand this. I have never broken a chain on any of my knolly's in the last 3 years (including 2 years on my DT). I'm very anal about my maintenance and replacing worn parts but I have been known to mash some pretty ignorant hills after being caught in the wrong gear. I also exclusively use sram crossstep chains for several years and have never had a failure on one of them. Probably 500km+ on my new Delirium this spring with no issues. There's got to be something with your setup and/or technique causing this. At least I don't remember you having quads like the governator when I rode with you.

  18. #18
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    just to put it out there, shimano chains MUST be reconnected using their self riveting pins, otherwise they will fail.

  19. #19
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    I think it is rider style. Some people have weak a$$ legs and they can shift uphill. I learned early on that if I am going up hill, I essentially shift under ZERO load. After a while it just became second nature to always upshift like that. Half a stroke of power, then coast while the cog runs up the ramp to the next gear, then back on the power.

    I think people get lazy and forget how to shift. Simply because you CAN shift under power does not mean you should.

    Having said that I still break a lot of chains, but doing things like pedalling a #110 pound bike for 3000 miles and 200,000 ft of elevation gain through mud and snow and sand, will do that. I am on my second season without a broken chain on my DT with Hammerschmidt and Alfine. No ramps, no cogs to go up or down, perfect chainline= indestructible chain.
    Attached Thumbnails Attached Thumbnails Chronic broken chains-knolly-dt-2010-002b.jpg  

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  20. #20
    shh. don't tell the wife
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    Good advice in here and the usual hunt for red herrings. In terms of technique how is it I rarely, if ever, broke chains on my SC Superlight in 8 years of riding yet have been through a 1/2 dozen chains and 1 derailleur on my DT in 1.5 years? In fact, I've never broken a derailleur in my 15 years of riding.

    I'm quite particular about my drivetrain maintenance. For example, I didn't like the feel of the threads in my derailleur hanger after one season so I replaced it as I thought it might have been putting my rear derailleur off its line.

    Upon inspection of my cassette the 32T's bend is definitely not great. There are also a few teeth here and there that look a tad bent.

    I also noticed my freewheel is notching in a bit near the bottom of the cassette. While there was some slight play in the cassette the freehub was solid so I'm thinking it might be the wear. I had to bin my Bontragger road wheels earlier in the season as I'd worn my cassette about 1/16" into the freehub body.
    All you need is love... but Scotch'll do in a pinch.

  21. #21
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    I've learned the hard way several times never to mix and match drive train components in regard to usage. There are different schools of thought on swapping chains once a month etc. I get the best wear by installing everything new, and let all the components wear together. I usually get 2 years without any trouble, and then replace everything when the "grinding" starts. In the past I tried replacing individual rings with disastrous results. It's amazing what works in the driveway at home and won't even function on the trail.

    BTW,
    The last time I had a little free play in the cassette, it was a broken rear axle.

    my .02, good luck

  22. #22
    shh. don't tell the wife
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    I know have a new cassettte, chain and rear derailleur. Last night the shifting was great and the chain didn't break.

    I also measured the positioning of my rear dropouts to ensure they are symmetric. When I have my wheel out I'll be sure to check the rear axle.
    All you need is love... but Scotch'll do in a pinch.

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