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Discussion Starter · #1 · (Edited)
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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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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Discussion Starter · #3 ·
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...
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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Discussion Starter · #5 ·
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?

After setting the proper height and angle, you have to set the stops. Then set the cable tension. If you have rubbing on the outside of the front mech while in the 11 and 12 in the back, my guess is the outer stop is too tight or the cable tension is insufficient. IOW, the front derailleur is not moved away from the frame enough.

Do some reading or watch youtube videos about setting up a front derailleur. If that fails, take the bike and $ to the LBS and have them adjust it.
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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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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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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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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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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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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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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Discussion Starter · #12 ·
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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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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8 hours ago I told you the solution.

Then Kerry agreed.

Then CX agreed.
 

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Take that as a signal that it's time to shift into your big ring and into the middle of your cassette
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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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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I agree as well :p
Then Swift agreed

Then Black agreed

Then Rolly agreed

If only there was this much agreement on other topics :eek: :D
 

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Then Swift agreed

Then Black agreed

Then Rolly agreed

If only there was this much agreement on other topics :eek: :D
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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