# Specialized crankset = CHAIN SUCK?!



## Pokey (Apr 15, 2006)

Anyone else experience chain suck with the specialized compact chainrings?

After a few good rides on my two week-old 09 Roubaix Pro D/A, I love everything but the chainrings.

I have been getting terrible chanin such when shifting from the large chainring to the smaller chainring on the compact set (34/50). The chain does not release from the big ring and gets wrapped around and has been scratching up the outside of my pretty D/A front derailleur. What a crock! Has happened four times in three rides. No shifting under crazy power or anything - just normal moderate tension.

Extremely disappointed! Makes the whole bike experience feel like I got duked into buying a very expensive item which turns out to be a cheap toy now.

Anyway, I took it back to the LBS and they offered to swap out the chainrings for some shimano rings. Not sure which one's they'll put on, R600 or R700 but I did not pay this much money for =<105-level components. Not sure if I should ask them to put specialized chainrings back on it. I have not heard of Specialized chain suck issues on here. I searched.

They said they have seen this issue before with specialized rings. That really irritates me though because I specifically asked about the Specialized crankset BEFORE I bought the bike and they flat-out told me they have not had any issues with the Specialized cranksets. I was trying to decide if the s-works would have been worth the extra $$. I was wondering why the s-works model comes with Shimano D/A cranks/chainrings and not the specializd crap. I guess I know now.

I am used to my s-works enduro SL MTB which has the new XTR stuff on it. I abuse the CRAP out of that drivetrain. Not purposefully, I just ride hard and fast and they have NEVER missed a shift ever! My FSA cranks on my old Roubaix also never missed a beat shifting.

</RANT>

EDIT: I also wonder if I'll have any spacing/chainline issues with the specialized bb30 bottom bracket/spesh crankset and shimano chainrings... Although I think the chainline and spacing from Specialized are already not a perfect match with the D/A front derailleur - it's pretty bad as-is.


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## ukbloke (Sep 1, 2007)

Sorry to hear that things aren't working out. For that kind of money, I'd expect everything to operate perfectly and for the LBS to make it right. You should get them to check whether Specialized have a recall on the chain-rings or crank-set, as sometimes Specialized does this on the quiet. I would also double-check everything myself, as the LBS can miss simple stuff. I'd check the FD cable tensions, limit positions, the FD height and carefully check that it is mounted correctly (not slipping). Is it braze-on or clamp?

Also, is the bottom bracket BB30? If it is, that does restrict the possible remedies. If not, you might want to insist on the LBS installing an Ultegra SL compact crank-set to make it good. I'd also check the chainline and, just to be sure, that the cassette is properly installed. Also check chain length and the RD setup while you are at it. If you don't feel comfortable doing this, get the LBS to check everything while you watch.


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## ukbloke (Sep 1, 2007)

Are you sure it is specifically chain suck, ie. the chain failing to disengage from the chain-ring teeth as it rotates off the bottom. How exactly does it scratch up the outside of the FD? Are you getting a bunch of links folded up around the FD cage? This could be pretty dangerous as your cranks could lock up instantly under pressure.

You should also check the chain for stiff links, and make sure that it is properly lubed. On new chains I like to get all the shipping gunk off before lubing. I suppose it could be an RD chain tension problem too, so again look at chain length and perhaps the B-screw adjustment on the RD.


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## Pokey (Apr 15, 2006)

ukbloke said:


> Are you sure it is specifically chain suck, ie. the chain failing to disengage from the chain-ring teeth as it rotates off the bottom. How exactly does it scratch up the outside of the FD?


Yep - it's an oversized BB. They don't call it a BB30 because that's a Cannondale technology name, but it's the same thing.

How does it scratch the outside of the FD? Imagine pedaling away in the large chainring. Then imagine releasing the FD from the large chainring when shifting so it now hovers over the small chainring. Imagine the chain not releasing from the large chainring and binding up between the teeth of the large and the teeth of the smal, thus not releasing from the big ring. As you complete the pedal stroke, the chain is stuck to the large chainring, thus pasing along the outside of the FD that hovers over the small chainring. Yes, it is quite dangerous



ukbloke said:


> You should also check the chain for stiff links, and make sure that it is properly lubed. On new chains I like to get all the shipping gunk off before lubing. I suppose it could be an RD chain tension problem too, so again look at chain length and perhaps the B-screw adjustment on the RD.



You gave me lots of good info - I have not checked chainlength nor b-tension screw on the RD. I did not realize there is a tension adjust for the FD return spring. I'll have to look for that. The limiters are all in the best possible spots.

I may play with it some more, but Chainsuck is usually solved by new chainrings.

The rest of the bike is briliant, but Specialized needs to go back to the drawing board on the chainrings.

I notice they don't offer these for sale on their web-site, only the s-works cranks and chainrings.

And yes, I promptly remove the sticky "shipping grease" with a chain cleaner and apply Rock-n-roll Extreme lube.


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## ukbloke (Sep 1, 2007)

Pokey said:


> I notice they don't offer these for sale on their web-site, only the s-works cranks and chainrings.


If it isn't a setup issue and is a design flaw in the chain-rings (and the LBS seems to have pretty much admitted as much), then how about pushing to get the S-works chain rings as warranty replacement? These would definitely be a nice upgrade! If they insist on Shimano chain rings, you should push for Ultegra or Ultegra SL rings to match the spec of your bike, rather than the older R600/R700 ones. I have the Ultegra compact cranks with a D/A drive-train on a Tarmac, and the front shifting is the best that I've ever experienced (flawless and smooth). I'm assuming that the BCD of the Specialized spider and its bolt pattern are the industry standard size for compact.


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## Pokey (Apr 15, 2006)

*Resolved!!!*

Well, I think I fixed it anyway.

Not only was I having chain suck shifting from the large to the small chainring, but I also seemed to have crappy shifting performance from the small chainring to the large chainring. Also the casette did not shift very smoothly (not as smooth as my old 7800 DA setup).

All this talk of setup, I thought I'd RTFM and follow all the setup procedures from scratch.

The first thing I read in the 7900 RD instructions was a note that said the 7900 chain had an inside edge and an outside edge and to set properly for best shifting performance. I do recall the inside and outside of the chain looking different. 

Lo and behold.... The assembler at the LBS put the chain on inside out. Couldn't make that much difference, right? WRONG!!!! I put it on the correct way, adjusted everythgin again and now I can't get it to chain suck!!!

There is still on point in the large chainring that seems a little sticky upon release, but it still releases. Before, the chain would get locked in there and take a small bit of force to pry it off.

Upon investigation (by me), it seems Shimano have altered the shape of the 7900 chain and simplified the tooth-profiles of the 7900 and Ultegra chainrings. Check out REI dot com for hi-res zoom-able images of the different chain rings. Previous chainrings had beveled edges on the outsides of the teeth for chain-relief during shifts. The newer chainrings (Ultegra and D/A) do not have this (compare with R700 chainring close-up). The downsde of those reliefs would be less softer aluminum material which would result in quicker wear. So it seems thay stopped altering the shape of the teeth and concentrated on optimizing the shapes of the steel chain link faces and created different shapes for inside edges (Where RD shifting takes place) and outside edges (where FD shifting takes place. Friggen shimano genius.

So at this point, I am not sure if I should do the FD700 (Ultegra-level) replacement chainrings that the LBS was ordering or if I should just demand new Specialized chainrings. No doubt some damage was caused to my chanrings when I had the chainsuck issues so I want them replaced. but I can't help but think that Shimano has done away with beveled chainring teeth for a reason (I am sure the insides are still beveled, but the outsides are no longer beveled)

But then either way, I'll have a disassembled and reassembled crankset. I would think the factory assembled are somehow more solid and done right without cutting corners like a LBS might do. MAybe I'll just use these as-is and see if the steel chain does not re-shape the teeth that have been nicked from the inside-out chain.

Yeah, I am one of those folks who does not just like to fix stuff by replacing it, but determining the cause of the failure in the first place.

I hope this short story helps someone. I'll update in a week or so to let you know if the chainsuck stops completely.

Cheers!


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## Dr_John (Oct 11, 2005)

Congrats on potentially figuring it out. Get the replacement Specialized rings, then find a different LBS.


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