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Spanish rider
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Discussion Starter · #1 · (Edited)
Hi all:

Today I noticed that the small ring on my SLX cranks seemed to be mounted wrong according to the teeth orientation. As you may know, the teeth of most rings are not symmetrical (apart from having different height), one side is more "ramped" than the other, which is more vertical.

Looking from the right side of the bike, the ramp is on the left side of every tooth of the big&middle ring. However, the small is different: the ramp is on the right side of every tooth.

I've searched the web and my cranks seem OK, or at least all the pictures I've seen look exactly as mine. The picture shows how mine looks:



The question is (asuming that mine and every other crank is properly mounted) , why is the small ring different from the other two?

I'm sure that it's related to shifting performance....
 

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I assume it's because of the direction that the chain moves: the ramp on the middle and large rings are to help the chain move from the smaller to the larger ring. I guess this is where it is needed most. Obviously when you move the granny you have to come from the larger middle ring.

But this is only a guess.

Tim
 

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Your chainring is OK. There should be no "shift ramps" on the left side of the granny ring as the ramps help lift the chain to the next ring, so only the mid and large rings would have them. More likely they are just release cutouts. Also, you'll see the the teeth are quite a bit longer than your mid ring and they "shark fin" points backwards aiding in the release to the next ring.
 

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Shimano instructions on chainring installation...

"The markings (stamped number on the side of chainring) on the intermediate and smallest chain ring should face inward (away from the crank arm), and the salient (small bulge on inside edge of chainring) aligns with the crank arm."
 
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