# orientation of my inner chainring



## paloaltorider (Jan 2, 2010)

Hello everyone,

I tried to research this but couldn't seem to get an answer. I've had the skating issue with my front chainring where the chain seems to skate in between the inner and outer chainring. It had been suggested that this could be due to a "flipped" inner chain ring. I've taken picture from the interior view of my chain rings and wanted to see if this is the reason for my skating issues. This is a sram rival compact crankset. Intuitively it seems that it is in the correct orientation but I wanted to check with the more experienced. Thanks a bunch!


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## PlatyPius (Feb 1, 2009)

The chainrings are oriented properly.


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## paloaltorider (Jan 2, 2010)

Thanks so much. Will futz with the fd next


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## FBinNY (Jan 24, 2009)

For future reference, the inner ring has a timing mark, which lines up with the crank arm. On yours it's the little tab on the inside circle. Other brands stamp a diamond or arrow, or whatever for timing.

Outer rings don't need a timing mark because the anti-jam pin serves that purpose.


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## Pieter (Oct 17, 2005)

FBinNY said:


> For future reference, the inner ring has a timing mark, which lines up with the crank arm. On yours it's the little tab on the inside circle. Other brands stamp a diamond or arrow, or whatever for timing.
> 
> Outer rings don't need a timing mark because the anti-jam pin serves that purpose.


Yep, except I have always studiously contravened these - on purpose, rotating the inner ring to a new position periodically to 'spread the wear' (as if that really helped all that much).

During 45000km of thusly riding chainsets with such marks, I have never had any issues as a result. One day I will have catastrophic chain suck, I know, and destroy the chainstay. But till then...:aureola:

Or am I missing something?


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## Opus51569 (Jul 21, 2009)

I don't know if this is universal to all rings, but in your case, the holes for the bolts are inset. Also, the labels are stamped so that they can be read from the outside.


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## FBinNY (Jan 24, 2009)

Pieter said:


> Yep, except I have always studiously contravened these - on purpose, rotating the inner ring to a new position periodically to 'spread the wear' (as if that really helped all that much).
> 
> During 45000km of thusly riding chainsets with such marks, I have never had any issues as a result. One day I will have catastrophic chain suck, I know, and destroy the chainstay. But till then...:aureola:
> 
> Or am I missing something?


Yes, and no. The phasing of the inner ring has little to do, with how the chain runs on the ring, and is only there as an aid to shifting. It ensures that the chain lines up best for shifting to the larger ring at the shift gate. When phased the chain moves smoothly (the glide in hyper glide) without the slippage of 1/2 tooth moving between the two chainrings.

It isn't a big deal, and being out of phase won't cause chain suck or any other problems.


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## wim (Feb 28, 2005)

Pieter said:


> Yep, except I have always studiously contravened these - on purpose, rotating the inner ring to a new position periodically to 'spread the wear' (as if that really helped all that much).


Well, good to know that I'm not the only one who still does this old-school squeeze-the-most-out-of-a-part thing. And like you, I'm not sure either if it's actually worth doing.


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## Pieter (Oct 17, 2005)

wim said:


> Well, good to know that I'm not the only one who still does this old-school squeeze-the-most-out-of-a-part thing. And like you, I'm not sure either if it's actually worth doing.


I am not sure if it helps. When a chain does not spread the load perfectly on all chainring teeth (which is inevitably the case at any given time), the teeth which engage on the 'power stroke' simply must do more work than the rest. And I do imagine I see evidence of this wear pattern. But not 100% convincingly.

Now, about squeezing the most out : my late lamented (stolen) bike with 2000 vintage Shimano 105 had a 39t ring which COULD be flipped. That was a big big help. Try that with any late model ring whereof the manufacturers have become wiser !!


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## yokeho (Nov 7, 2010)

FBinNY said:


> Yes, and no. The phasing of the inner ring has little to do, with how the chain runs on the ring, and is only there as an aid to shifting. It ensures that the chain lines up best for shifting to the larger ring at the shift gate. When phased the chain moves smoothly (the glide in hyper glide) without the slippage of 1/2 tooth moving between the two chainrings.
> 
> It isn't a big deal, and being out of phase won't cause chain suck or any other problems.


Thanks, that helped me understand why ther is inner chinring indexing. 

I just bought an FSA 36T inner chainring and it has two indexing marks. It looks like one is labelled to be used for a 36/50 combo and the other for a 36/52.

The problem is I'm setting up a 36/48 cyclocross crank so don't know which one to pick! Any ideas?


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## FBinNY (Jan 24, 2009)

yokeho said:


> Thanks, that helped me understand why ther is inner chinring indexing.
> 
> I just bought an FSA 36T inner chainring and it has two indexing marks. It looks like one is labelled to be used for a 36/50 combo and the other for a 36/52.
> 
> The problem is I'm setting up a 36/48 cyclocross crank so don't know which one to pick! Any ideas?


Long before gated shifting, I'd phase inner rings by trial and error. I'd assume the rider would shift when the pedals were vertical, and would lead the chain off the outer ring there, and down to the inner. I'd try the 5 positions looking for the one where the teeth lined up best. 

You can use the same method which is easier now because the shift point is fixed. lead the chain through the shift gate and find the best phase for the inner. Odds are you wont get it perfect, so from experience, let the ring be a bit behind rather than ahead of perfect. Then the chain will shift back an bit and drop in.


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