# Chain rubbing on big chain ring



## Rarely.Seen (Aug 22, 2016)

Will buying spacers get rid of this problem? I am using a GXP 53/39 with an 11-25 (Sram red). The rubbing occurs on the two top gears (11T and 12T. When set on the smallest chainring (39) the chain rubs slightly on the biggest chain ring (53)

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## Migen21 (Oct 28, 2014)

how in the world can we know what's wrong with that little bit of information?

I mean you didn't even tell us what brand, model, etc... 

Is it only in one gear? or all the time? 

I've personally never heard of having to use spacers to keep my chain from rubbing on anything...


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## Rarely.Seen (Aug 22, 2016)

Migen21 said:


> how in the world can we know what's wrong with that little bit of information?
> 
> I mean you didn't even tell us what brand, model, etc...
> 
> ...


You're right Sorry for the lack of info given. I am using the Sram red groupset and the chain rubs on the top two gears. (11T and 12T). After passing those gears everything seems to be running perfect 

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## crit_boy (Aug 6, 2013)

Deletion - Edit flowing from OP edit.


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## Rarely.Seen (Aug 22, 2016)

crit_boy said:


> At the risk of being told I don't know what I am talking about. . .
> 
> Sounds like your front derailleur is not adjusted properly. Did you adjust it after you replaced your old 36/52 with your new 39/53?
> 
> ...


Yeah I adjusted it after switching to the 53/39. I left 1mm then 2mm to see if anything would change but nothing I am pretty sure everything else is in perfect order. I'll take pics of the front derailleur in the morning and if all else fails then I'll take it to my Lbs :/ 

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## Migen21 (Oct 28, 2014)

So the chain is rubbing on the outer edge of the front derailleur when the chain is on the big chainring in front, and the smallest cogs in the back?

Check your high limit screw, derailleur height, check if it's aligned with the face of the chainring (in accordance with SRAM documentation), and lastly (and most obviously) cable tension.

You don't mention what crankset you are using, or what type of bottom bracket, but unless you are using something very non-standard, or there is something amiss with your chain line, there is no reason you should need spacers to prevent your chain from rubbing.


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## bikerjulio (Jan 19, 2010)

After careful reading of the thread I am unsure what the problem is.

Unless we are talking extreme cross-chaining, how can the chain rub on the big ring?

OP, if this happens in the small chainring - small cogs combo, then it's not uncommon, and the cure is simple - don't do it.


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## Jay Strongbow (May 8, 2010)

bikerjulio said:


> After careful reading of the thread I am unsure what the problem is.


Same here. And despite not knowing the problem I can't imagine what spacers could do to correct whatever it may be. Or where you intend to put said spacers.

Does sound like you just need to set up the der properly.


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## Kerry Irons (Feb 25, 2002)

bikerjulio said:


> After careful reading of the thread I am unsure what the problem is.
> 
> Unless we are talking extreme cross-chaining, how can the chain rub on the big ring?
> 
> OP, if this happens in the small chainring - small cogs combo, then it's not uncommon, and the cure is simple - don't do it.


The OP edited his post to say small ring, smallest two cogs in the back. 

1. Common problem, though not universal with every setup

2. Using BB spacers would probably mess up the chain line, though if the chain line is off it might help.

3. Obviously derailleur adjustments have nothing to do with this.

4. If the chain line is right and the chain rubs, then Julio's advice is perfect: don't ride in these gears. Running at this end of the cassette is a formula for more rapid chain and cassette wear and a slight increase in drivetrain friction.


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## cxwrench (Nov 9, 2004)

This has nothing to do w/ the front derailleur. The OP says his chain is hitting the big ring when he's on the small ring and the 2 smallest cogs. I haven't looked lately but it was previously stated in both SRAM and Shimano service instructions that you might not be able to use the _3 smallest cogs when in the small ring because of interference w/ the big ring_. It's normally more of a problem w/ compact cranks because of the great difference in size between small and large rings. Chain stay length also comes into play. 

The OP can adjust his derailleur over and over but it won't make any difference. What he can do to stop this from happening is obvious. Stop cross chaining small/small.


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## Migen21 (Oct 28, 2014)

cxwrench said:


> This has nothing to do w/ the front derailleur. The OP says his chain is hitting the big ring when he's on the small ring and the 2 smallest cogs. I haven't looked lately but it was previously stated in both SRAM and Shimano service instructions that you might not be able to use the _3 smallest cogs when in the small ring because of interference w/ the big ring_. It's normally more of a problem w/ compact cranks because of the great difference in size between small and large rings. Chain stay length also comes into play.
> 
> The OP can adjust his derailleur over and over but it won't make any difference. What he can do to stop this from happening is obvious. Stop cross chaining small/small.


I wondered about this. His description of the problem is so poor, I really wasn't sure.

I interpreted his thread topic to mean his chain rubs when it's on the big ring, not rubs on the big ring (just because it's a far more likely scenario). Of course, I could be completely wrong.

Hopefully he'll come along and clarify for us...


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## Rarely.Seen (Aug 22, 2016)

Migen21 said:


> I wondered about this. His description of the problem is so poor, I really wasn't sure.
> 
> I interpreted his thread topic to mean his chain rubs when it's on the big ring, not rubs on the big ring (just because it's a far more likely scenario). Of course, I could be completely wrong.
> 
> Hopefully he'll come along and clarify for us...


Cx wrench got the whole idea. I edited the post with more onfo.
Sram red groupset
GXP 
53-39 w 11-25
Rubbing occurs on 11T and 12t and it happens when I switch to the 39. The chain rubs on the 53. I adjusted the cable tension and the both derailleurs but nothing has changed 

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## bikerjulio (Jan 19, 2010)

Rarely.Seen said:


> Cx wrench got the whole idea. I edited the post with more onfo.
> Sram red groupset
> GXP
> 53-39 w 11-25
> ...


8 hours ago I told you the solution.

Then Kerry agreed.

Then CX agreed.


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## SwiftSolo (Jun 7, 2008)

Take that as a signal that it's time to shift into your big ring and into the middle of your cassette


Rarely.Seen said:


> You're right Sorry for the lack of info given. I am using the Sram red groupset and the chain rubs on the top two gears. (11T and 12T). After passing those gears everything seems to be running perfect
> 
> Sent from my SM-G935T using Tapatalk


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## blackfrancois (Jul 6, 2016)

sheldon brown said:


> Generally, the large outer chainring shouldn't be used with the largest rear sprocket, because of the sharp angle [the chain] creates. Similarly, the small inner chainring shouldn't be used with any of the smaller rear sprockets.
> 
> The small-small combinations create extra problems besides the bad angle. The smaller the front chainring, the greater the pull on the chain; the smaller rear sprockets only engage a very few teeth with a very few chain rollers at any one time, so stresses are concentrated. If you make a habit of abusing the small chainring of a triple crank by using it with the smaller rear sprockets, you will drastically increase the wear rate of both chain and sprockets.


from Gear Theory for Bicyclists


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## Roland44 (Mar 21, 2013)

bikerjulio said:


> 8 hours ago I told you the solution.
> 
> Then Kerry agreed.
> 
> Then CX agreed.


I agree as well


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## bikerjulio (Jan 19, 2010)

Roland44 said:


> I agree as well


Then Swift agreed

Then Black agreed 

Then Rolly agreed

If only there was this much agreement on other topics


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## cxwrench (Nov 9, 2004)

I fully agree w/ my post.


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## bmach (Apr 13, 2011)

That's funny, cx


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## Lombard (May 8, 2014)

bikerjulio said:


> Then Swift agreed
> 
> Then Black agreed
> 
> ...


Agree here too. There is no way to prevent this rubbing in the small/small combo. Believe me, I tried by adjusting the FD cable and ended up with chain drop issues. So you have only two choices. You can either not use the small/small combo OR you can just live with the noise and the eventual grooving of your FD. Period.


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## Tachycardic (Mar 31, 2013)

Go to a 1x setup. I guarantee that you won't have problems with chains rubbing on chain rings


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## bikerjulio (Jan 19, 2010)

This is the most agreeable thread ever in the history of threads. It's a Festivus miracle!


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## duriel (Oct 10, 2013)

Just take the big ring off, then it will not rub... ever.
I'm not aggreable.


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## Lombard (May 8, 2014)

Patient: It hurts when I do that. Doctor: Then don't do that.


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## bikerjulio (Jan 19, 2010)

The late great Tommy Cooper (you have to be English probably to know of him), had a variation:

"I went to the Doctor, and I said "Doctor I've broken my arm in several places". Doctor says "well don't go to those places"." :7:


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## Kerry Irons (Feb 25, 2002)

Lombard said:


> Agree here too. There is no way to prevent this rubbing in the small/small combo. Believe me, I tried by adjusting the FD cable and ended up with chain drop issues. So you have only two choices. You can either not use the small/small combo OR you can just live with the noise and the eventual grooving of your FD. Period.


Rubbing is on the chain ring, not the FD cage. The grooves will be on the inside of the big ring.


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## mieszko_I (Aug 19, 2006)

Sorry to dig up this old thread, but not much out there in regards to C2 crank compatibility issues.

I understand the OP's frustration, I have an Aluminum 68mm English Threaded BB with eTAP Gxp that is plagued by the same exact issue. 

However, I am able to cross-chain all day long with my Di2 bike without the chain rubbing on the inside of the big ring (using both, 6800 & SiSl w/Opi Cranksets).

I also went through a lengthy exercise, in which I transferred the Etap groupset onto my Di2 Bike (BB30 S-Works Tarmac w/Cannondale SiSl OPI Crankset), obviously I could not use the Red GXP Crankset. All worked fine in any combination without the chain rubbing on the inside of the large chainring.

SRAM mentions chainstay length as a likely culprit, but I also don't have any issues with cross-chaining on a 2 sizes smaller frame (shorter chainstays) using 6800 cranks. That bike is also a 68mm threaded BB (so apples-to-apples...sort of). 

Yes, we all know that cross chaining is "bad" and wears components quicker, but to me it seems that in this case it is the Sram Red Crankset, more specifically the chunky machining (on inside of the large chainring), along with tight spacing between rings.

Like the OP, I too thought about running 1~2mm spacers between the the "Large Chainring and spider" to push it out just a tad and give the small ring enough clearance to accommodate the chain in those extremes. Not sure if it's doable, or how drastically that would affect the chainline while in the large ring, but might work.

I do understand that the 11sp chain is narrower, and increasing the distance between the chainrings can potentially lead to the chain getting jammed between rings during shifts, but I doubt that the addition of a 1mm spacer would lead to this. 

Lastly, I have not measured the clearance between the chainrings on the cranksets which work flawlessly with Di2 and eTap in all gear combination, but it seems clear that it must be different...and BTW I am running Dura-Ace CN-HG901 chains on all my drivetrains.


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## cxwrench (Nov 9, 2004)

mieszko_I said:


> Sorry to dig up this old thread, but not much out there in regards to C2 crank compatibility issues.
> 
> I understand the OP's frustration, I have an Aluminum 68mm English Threaded BB with eTAP Gxp that is plagued by the same exact issue.
> 
> ...


It's quite simple. Don't cross chain small/small. Only use what works, there is no sense in using small/small. Do NOT put any spacers under your big ring. There are more engineers designing these systems than you can shake a stick at and they all have the same answer to this issue.


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## 202cycle (Sep 13, 2011)

> I do understand that the 11sp chain is narrower, and increasing the distance between the chainrings can potentially lead to the chain getting jammed between rings during shifts, but I doubt that the addition of a 1mm spacer would lead to this.


It would most certainly lead to this. The indexing of the front shifter is designed to work with the spacing of the chainrings WITHOUT modification. If you move the large chainring outbound 1 mm (which might as well be a mile in terms of front derailleur adjustment), then the index cable tension to reach that chainring would be so high, you would never be able to shift back down to the small ring. With the additon of the extra 1mm between rings, when you did shift back down, the chain would not go all the way to the small ring and most likely jam in the space between.

I cannot for the life of me understand why people feel the need to ride in the small/small, and would consider modifying precision shifting systems just to make that possible.


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## Lombard (May 8, 2014)

202cycle said:


> I cannot for the life of me understand why people feel the need to ride in the small/small, and would consider modifying precision shifting systems just to make that possible.


This. Small/small and large/large were not designed to be ridden. There is absolutely no reason to use either of these besides laziness.


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## cxwrench (Nov 9, 2004)

Lombard said:


> This. Small/small and large/large were not designed to be ridden. There is absolutely no reason to use either of these besides laziness.


Not so fast. Big/big is something that should work and needs to work. Small/small is just dumb.


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## Lombard (May 8, 2014)

cxwrench said:


> Not so fast. Big/big is something that should work and needs to work. Small/small is just dumb.


Why would you ever need big/big?


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## cxwrench (Nov 9, 2004)

Lombard said:


> Why would you ever need big/big?


Because you don't want to risk a front shift. Racers do it ALL the time. Or, look at it this way. Out of the box, the new Di2 won't allow shifts to small/small or even the small/12. But it will definitely allow you to go big/big. To a LOT of people big/big makes sense every now and then. Trust me on this one.


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## Lombard (May 8, 2014)

cxwrench said:


> Because you don't want to risk a front shift. Racers do it ALL the time. Or, look at it this way. Out of the box, the new Di2 won't allow shifts to small/small or even the small/12. But it will definitely allow you to go big/big. To a LOT of people big/big makes sense every now and then. Trust me on this one.


Well OK, I guess if you are a racer, it is prudent to avoid front shifts. A chain drop can lose a race. And I presume many racers are strong enough that they seldom use small ring. 

For myself, I generally shift the front when I'm in one of the middle cogs in back. If I'm in the small ring and getting near the small in back and want more speed, I shift to the large ring. If I'm in the large ring and I see a hill ahead, I immediately go to the small ring. So neither extreme is necessary for me.


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## velodog (Sep 26, 2007)

Lombard said:


> This. Small/small and large/large were not designed to be ridden. There is absolutely no reason to use either of these besides laziness.


I don't see an issue with large\large, but by the time small\small is arrived at the big ring should be engaged. Shifting into bigger gears is probably going to be more long term than smaller gears.


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