# Anyone else annoyed by 34-12 & 34-11 being un-usable ?



## mtberv (Sep 29, 2005)

*Anyone else annoyed by 39-12 & 39-11 being un-usable ?*

I have noticed an annoyance on many bikes (09 and 2010) running sram red.
The 39-11 causes the chain to rub the large chain ring while making a popping noise as the chain tries to suck into the large chain ring.
I also have noticed rubbing of the chain on the 53 front chain ring in the 39-12.

I know you are not supposed to "cross-chain" however I never had any issues spinning these cross-chained gears out on a campy setup.

I contacted Sram tech support about this & they comment that there is nothing that can be done. 
In fact, they can do something, they could change the chain line by changing the width of the BB cups etc... or offer some kind of alternate spacer BB cup set.

Any thoughts on this besides "use your 53" lol?


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## Guest (Nov 6, 2009)

Would riding 53x15 or 16 really be that hard, even if you could why would you induce extra wear on your components just to stay in the little ring?


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## asad137 (Jul 29, 2009)

I can see how it would be annoying if you're on terrain that has you in the little ring most of the time and it could save you from shifting to the big ring. Almost never happens to be but I live in the Midwest.

Asad


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## ultimobici (Jul 16, 2005)

mtberv said:


> I have noticed an annoyance on many bikes (09 and 2010) running sram red.
> The 39-11 causes the chain to rub the large chain ring while making a popping noise as the chain tries to suck into the large chain ring.
> I also have noticed rubbing of the chain on the 53 front chain ring in the 39-12.
> 
> ...


The likely reason is that Campagnolo's front shifting is not a "one click, and you're there" but a winch-like system. Consequently it doesn't require prominent pick up teeth on the inside edge of the chainring.

That said, why use a combination that puts more strain on the chain than the alternative with the attendant friction? Only means more effort!


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## mtberv (Sep 29, 2005)

ultimobici said:


> The likely reason is that Campagnolo's front shifting is not a "one click, and you're there" but a winch-like system. Consequently it doesn't require prominent pick up teeth on the inside edge of the chainring.
> 
> That said, why use a combination that puts more strain on the chain than the alternative with the attendant friction? Only means more effort!


The problem is with the chain line. The crankset needs to be pushed out 1mm on the drive side.


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## ukbloke (Sep 1, 2007)

mtberv said:


> The problem is with the chain line. The crankset needs to be pushed out 1mm on the drive side.


Out of the box thinking ... can you pull in the chain-line by 1mm by removing the 1mm spacer between the cassette and the wheel? This spacer is present for 10 speed cassettes running on 9/10-speed compatible free-hubs. Of course, you will likely need the 1mm spacer on the other side of the cassette between the smallest cog and the lock ring. You'll also need to check carefully for clearance between the chain, cassette and RD versus the drive-side spokes. The RD limits and tension would obviously need to be set up again for the new position.


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## ultimobici (Jul 16, 2005)

mtberv said:


> The problem is with the chain line. The crankset needs to be pushed out 1mm on the drive side.


Unless your frame is out it is not a problem with chainline.

At present you can use 53 x 23 or what ever your largest combination is without risk of the chain dropping. If you "fix" the 11 & 12 it may not work especially if your chainstays are short.

Plus why do you need an 11 if you have a 53? 

Learn to spin!!


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## mtberv (Sep 29, 2005)

ukbloke said:


> Out of the box thinking ... can you pull in the chain-line by 1mm by removing the 1mm spacer between the cassette and the wheel? This spacer is present for 10 speed cassettes running on 9/10-speed compatible free-hubs. Of course, you will likely need the 1mm spacer on the other side of the cassette between the smallest cog and the lock ring. You'll also need to check carefully for clearance between the chain, cassette and RD versus the drive-side spokes. The RD limits and tension would obviously need to be set up again for the new position.


There is no 1mm spacer on the freehub body on any sram red bike I have built.


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## Mapei (Feb 3, 2004)

To my eyes, if SRAM doesn't allow you to go small-small it points up a flaw in the design that just should not exist. 

It reminds me of the windshield wipers on my 2000 Audi A4. If it wasn't pouring down rain, the wipers would judder. It didn't matter what speed the wipers were running at. It didn't matter how fresh the blades were. I got hold of Audi so that it could be fixed under warranty and the representative told me they're "working on a solution to the problem." Audi and other companies have been putting windshield wipers on cars for eighty years. I never had the problem with my BMW's, Mercedes, or Honda. Wha?


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## ukbloke (Sep 1, 2007)

mtberv said:


> There is no 1mm spacer on the freehub body on any sram red bike I have built.


OK, fair enough. It makes sense that they would have built this into the cassette rather than adopting Shimano's ill-fated 10-speed-only hub spacing idea.


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## Guest (Nov 14, 2009)

Mapei said:


> To my eyes, if SRAM doesn't allow you to go small-small it points up a flaw in the design that just should not exist.
> 
> It reminds me of the windshield wipers on my 2000 Audi A4. If it wasn't pouring down rain, the wipers would judder. It didn't matter what speed the wipers were running at. It didn't matter how fresh the blades were. I got hold of Audi so that it could be fixed under warranty and the representative told me they're "working on a solution to the problem." Audi and other companies have been putting windshield wipers on cars for eighty years. I never had the problem with my BMW's, Mercedes, or Honda. Wha?



I don't see the comparison between not being able to shift into a gear you already have and windshield wipers not working.


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## davidka (Dec 12, 2001)

This is not a new problem, it has been happening since the 8 speed days and has occurred on every road bike I have owned since 1992 (while I have never owned a campy bike, most of the ones I've worked on had the same issue). The only "fix" without changing the chain line is a longer chain stay to reduce the angle of the chain.

The answer, even though you asked not to hear it, is don't use that gear. Even if it didn't accelerate chain wear it's far less efficient than an equivalent gear from the large ring.


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## mtberv (Sep 29, 2005)

davidka said:


> This is not a new problem, it has been happening since the 8 speed days and has occurred on every road bike I have owned since 1992 (while I have never owned a campy bike, most of the ones I've worked on had the same issue). The only "fix" without changing the chain line is a longer chain stay to reduce the angle of the chain.
> 
> The answer, even though you asked not to hear it, is don't use that gear. Even if it didn't accelerate chain wear it's far less efficient than an equivalent gear from the large ring.


So you accept not being able to use the 39-12 and 39-11 ?

I own a campy chorus 10 speed bike that you can use the 39-11 on all day long without issues...

This issue is not nearly that bad on a 2010 durace bike. 

The 34-12 can't even be used on several sram red bikes I have ridden (brand new from giant and fuji).


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## davidka (Dec 12, 2001)

mtberv said:


> So you accept not being able to use the 39-12 and 39-11 ?


Yes. I always saw it as acceptable. I never wanted to go to those gears anyway. A larger ring/cog keeps the chain under better tension and is more efficient.

More than accept it, I warn against it, chainsuck can happen easily because of it. That can lead to a disaster on a carbon frame. Usually happens in a competitive situation when a rider is grabbing gears over the top of a hill and runs down the cogs instead of reaching for the big ring. The pickup pins grab the lower run of the chain (under only the light tension of the rear derailleur) and draws it up into the chainstay.


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## mtberv (Sep 29, 2005)

Chain suck in a 39-12 or 39-11? 
I have never seen it occur.


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## crj (Jul 31, 2006)

Guy that I ride with recently went from Campy on his Scott of 5 years to Scram on his new Ridley and he has the same issues. We are used to using all of the cassette in either chain ring with Campy with no issues. He hasn't said he hates the Scram yet but it won't suprise if he shows up with Campy on his Ridley one day.


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## TucsonMTB (Aug 3, 2008)

You guys piqued my interest, so I tried the 34-12 and 34-11 combinations while riding today. It seems like a frame geometry issue. My 56 cm Scott Addict R4 came with SRAM Rival throughout. At 1700 miles, I changed to a Dura-Ace chain, but otherwise it is as provided by Scott and does NOT have an issue with either of these combinations. There is NO derailleur rub and NO clanking of the chain on the outer chain ring. :thumbsup: 

On their geometry chart, Scott lists the chain stay length as 15.9 inches or 405 mm.


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## davidka (Dec 12, 2001)

mtberv said:


> Chain suck in a 39-12 or 39-11?
> I have never seen it occur.


I have, it's more likely to happen if the chain was mounted on the longer side of correct length becaue of less spring tension in the rear derailleur. It doesn't occur a lot but it sure can do some non-warranty covered damage.


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## thechriswebb (Nov 21, 2008)

Man, I know that this thread probably doesn't need another person to give the same answer, but it is the right one. There is really no reason for you to be in that gearing. It is inefficient and bad for your drive train. No component manufacturer designs their equipment to be operated in that manner. Just because it is possible to shift into that combination does not mean that it should operate just as well in it. That is what the big chain ring is for. 

It would be "possible" to drive your automobile with manual transmission at speeds that are inappropriate for the gearing that you choose, but you would either lug your engine or overheat it due to RPM's that are too high. If you complained to your auto mechanic that your engine was lugging when going 20 mph in 4th gear, or if you tried to have your engine replaced under warranty because you blew it driving 70 in 2nd gear, you would be out of luck. I suppose that you could argue that since it is "possible" to drive in those speed/gearing combinations that the vehicle should operate fine in them. You could also argue that you drove that way because it was annoying to have to shift into the proper gearing, but either way the mechanic would probably laugh at you. Why should it be any different with bikes? Anyone and everyone that rides will tell you that a 39/11 or 39/12 gearing is inappropriate, which you obviously know because you said so in your original post. 

I am not pretentious enough to believe that I know everything or to believe that "group think" is always correct, but maybe the fact that 90% of the people here would answer that question with "don't use that gearing" warrants consideration that perhaps that is the correct answer. 

-Chris-


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## mtberv (Sep 29, 2005)

My point is, the 39-11 or 39-12 have issues on SRAM red. I don't have any issues with campy or shimano bikes in those gears.

Believe it or not, the 39-12 is a useful gear when you are riding short sweeping hills etc.


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## Guest (Nov 18, 2009)

mtberv said:


> My point is, the 39-11 or 39-12 have issues on SRAM red. I don't have any issues with campy or shimano bikes in those gears.
> 
> Believe it or not, the 39-12 is a useful gear when you are riding short sweeping hills etc.


The front mech is pretty useful too.


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## thechriswebb (Nov 21, 2008)

mtberv said:


> My point is, the 39-11 or 39-12 have issues on SRAM red. I don't have any issues with campy or shimano bikes in those gears.
> 
> Believe it or not, the 39-12 is a useful gear when you are riding short sweeping hills etc.


 alright


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## XR4Ti (Jul 8, 2008)

Straight from the horse's mouth:


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## SwiftSolo (Jun 7, 2008)

mtberv said:


> My point is, the 39-11 or 39-12 have issues on SRAM red. I don't have any issues with campy or shimano bikes in those gears.
> 
> Believe it or not, the 39-12 is a useful gear when you are riding short sweeping hills etc.


You'll find that, too often, these discussions are pointless because few people ride in the same conditions as you. On fast moving group rides in short, steep rollers, being able to cross up your chain for short periods is important.

It is funny that the same groupo that allows you to drop or pick up three cogs at the same instant that you shift chainrings is the one that allows cross shifting (campy 11). That ability eliminates that temporary "wrong gear" problem that occurs on others immediately after changing chain rings.


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## davidka (Dec 12, 2001)

I don't think that Campy's supposed (the ones I've experienced have the same chain rub) ablilty to use crossed gearing makes it any better for the drivetrain to do it. All the same downsides exist.


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