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  1. #1
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    Are middle chain rings interchangeable?

    I'm going 2x9 but want a 36t instead of the stock 32t. Are all middle 104BCD rings interchangeable as long as they have ramps?

  2. #2
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    Quote Originally Posted by dunerinaz
    I'm going 2x9 but want a 36t instead of the stock 32t. Are all middle 104BCD rings interchangeable as long as they have ramps?
    more or less, if the bolt pattern is the same. what are you thinking as far as brands

  3. #3
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    I'm interested in dong the exact same thing. Dropping my 44 and replacing the 32/22 with 36/24. Truvativ Stylo cranks. So can I use any brand of rings so long as they have the same bolt pattern? What do mean when you say ramps?
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    Quote Originally Posted by chuckie33
    I'm interested in dong the exact same thing. Dropping my 44 and replacing the 32/22 with 36/24. Truvativ Stylo cranks. So can I use any brand of rings so long as they have the same bolt pattern? What do mean when you say ramps?
    ramps and pins are on the back side of the rings , they aid in shifting

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    The pins, ramps and gates (cut down teeth) help pick up the chain when shifting from a smaller sprocket, similar to the way the modified cassette teeth improve shifting. That's why there smallest sprocket is of conventional cut.

    A second consideration is phasing. Today's Xxxxxglide (pick a name) shifting depends on the two adjacent sprockets being phased to each other so that as the chain moves from one to the other at the intended shift gate, the rollers will drop neatly onto the new sprocket instead of lining up with the tops of the teeth. That's why most of the outermost rings are marked with the size of the inner ring they're matched to.

    If you change only one chainring, or mix brands, you lose this exact phasing and therefore some degree of shift response. However (if the number of teeth isn't a multiple of the number of bolts) you can rotate a chainring trying each mounting position to find the sweet spot with the best shifting action. This is what we did for race bikes back in the bronze age before gated (xxxxglide) shifting.
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  6. #6
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    some rings need spacers too.. seems like *most* dont.

    i have shimano ultegra rings on my road FSA crank, and ran xt rings on my girlfriends fsa mtn.

  7. #7
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    Quote Originally Posted by FBinNY
    The pins, ramps and gates (cut down teeth) help pick up the chain when shifting from a smaller sprocket, similar to the way the modified cassette teeth improve shifting. That's why there smallest sprocket is of conventional cut.

    A second consideration is phasing. Today's Xxxxxglide (pick a name) shifting depends on the two adjacent sprockets being phased to each other so that as the chain moves from one to the other at the intended shift gate, the rollers will drop neatly onto the new sprocket instead of lining up with the tops of the teeth. That's why most of the outermost rings are marked with the size of the inner ring they're matched to.

    If you change only one chainring, or mix brands, you lose this exact phasing and therefore some degree of shift response. However (if the number of teeth isn't a multiple of the number of bolts) you can rotate a chainring trying each mounting position to find the sweet spot with the best shifting action. This is what we did for race bikes back in the bronze age before gated (xxxxglide) shifting.

    Agree 100%, however, granny rings have none of these features, so there is no phase to match (except possibly leg strength input/pulse) when considering a two ring system like this....unlike what you would have with multiple rings that have gates/ramps/pins.

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    dan0, I hadn't really narrowed it down to a specific brand yet. I have truvativ firex cranks that came with trushift rings. Truvativ makes 36t trushift rings, I just wondered if there was a higher quality ring in another brand that would last longer. Any specific suggestions?

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    Quote Originally Posted by dunerinaz
    dan0, I hadn't really narrowed it down to a specific brand yet. I have truvativ firex cranks that came with trushift rings. Truvativ makes 36t trushift rings, I just wondered if there was a higher quality ring in another brand that would last longer. Any specific suggestions?
    shimano slx makes a 36 with ramps
    action tec makes a ti version , dont think it has ramps though
    the Ti version would last the longest but its pricey

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