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  1. #1
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    Blackspire Chainring Configuration

    My new set of 3 Blackspire Chainrings came in today.

    There are no installation instructions and nothing on their website for the rings.

    Does it matter what position they are installed relative to each other? There are stainless steel pins and machined cutouts in the large and middle rings. Do these need to be lined up in a specific way to better shift from one to another or is one not dependent on the other?

    Also, do these ramps and pins need to be lined up in specific position in relation to my crank? For example, does it need to be installed to take advantage of the forces at the top of my pedal stroke?

    Hopefully the pic helps.
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  2. #2
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    For optimal performance gated chainrings should be phased so thet the correct part of the chain lines up with the ramps and gates (cutout teeth). I don't know about Black Spire, but take a look and see if there's a mark of some kind on each ring. If so, they should all line up with the crank arm, or at least each other.

    To phase unmarked rings, lay the outer flat with the middle one on top with the holes lined up. (this might be easier on the crank laying flat on a table) Wind a length of chain around the middle ring and lead it up the ramp and through the gate onto the outer ring. Try this in all 5 (or 4) possible positions moving the middle ring and you want to use the one where the chain lines up best with the teeth of the receiving ring. Repeat the process with the middle and inner rings.

    Now when you mount it all together the chain will be correctly phased to catch the teeth of the recieving ring each time you shift. You can also time the shift to occur at or near the 12/6 O'clock position of the crank - when the load is the least - by rotating the entire set to a different bolt position.

    Once you have everything to your liking, paint or scratch a phase mark into each ring so you can duplicate it easier next time. You might also take a photo showing the ideal orientation and save it for your next set of rings.
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  3. #3
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    Blackspire, like most other ring manufacturers, puts little pips on the rings that should all line up under the crankarm.
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  4. #4
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    With regards to the granny gear, it doesn't matter since it doesn't have any ramps like the middle and outer rings, you can mount it however. But like the previous poster mentioned to get effective shifting you have to mount the middle/outer with the "pips" aligned with the crankarm.

  5. #5
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    Thanks everyone! I totally missed those pips on these Blackspires! My last set, RaceFace had the marks and it was easy. This helps a lot.

    Based on the picture it looks like I set it up in the worst possible config, none of them are lined up...haha.

    As a side note, I've noticed that the large Blackspire chainring does not have the pin on the outboard side like my last set. From what I understand this pin is there in case you dump your chain on the outboard side of the big ring to prevent it from getting chain sucked between your big ring and crank arm. I guess I will have to be extra careful.


    RED5, that avatar pic owns.

  6. #6
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    Quote Originally Posted by RED5
    With regards to the granny gear, it doesn't matter since it doesn't have any ramps like the middle and outer rings, you can mount it however. But like the previous poster mentioned to get effective shifting you have to mount the middle/outer with the "pips" aligned with the crankarm.
    Minor correction-

    With gated shifting the phase of both the from chainring and the to chainring are equally important. During the shift the chain will be partly engaged on both, and if it starts in the wrong place it won't phase correctly during the shift.

    Quote Originally Posted by KaizerSozay
    Thanks everyone! ....

    As a side note, I've noticed that the large Blackspire chainring does not have the pin on the outboard side like my last set. From what I understand this pin is there in case you dump your chain on the outboard side of the big ring to prevent it from getting chain sucked between your big ring and crank arm. I guess I will have to be extra careful.
    If the gap between the arm and chainring is narrower or much wider than the chain, no problem. But if the gap is the right size for the chain to slide in and then jam, you'll want a pin.

    You can make your own. Visit the hardware store and buy a #2 brass or SS flathead screw, and a bunch of nuts. Drill and countersink the chainring from the between-the- chainrings side. Drop in the screw, and use as many nuts on the other side as required to make a pin the right length. Once you've got it, glue or Locktite the last one on.
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  7. #7
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    Quote Originally Posted by FBinNY
    Minor correction-

    With gated shifting the phase of both the from chainring and the to chainring are equally important. During the shift the chain will be partly engaged on both, and if it starts in the wrong place it won't phase correctly during the shift.
    Odd, I've never seen a granny with a "pip" on it, but if you have then I'd guess you may have a point. Either way since granny rings don't have "ramps" or "gates" I still don't see how it matters.

  8. #8
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    Long before (I'm afraid to tell you how long) Shimano introduced gated shifting (uniglide) race mechanics like myself were phasing chainrings to optimize shifting.

    At the time there were no ramps or gates, but by rotating the chainrings we could control where the chain was best lined up to smoothly make the shift, and position the rings so that was when the cranks were near 12/6 o'clock, or between the power strokes.

    With todays rings they position the gate so the shift happens at the right time, but the phase of the from ring determines whether the chain is correctly lined up to engage as it comes through the gate. When perfectly phased the chain drops in and engages immediately, When the phasing is off, It rides the top until it lines up then drops in giving you that little bit of skip at the end of the shift.

    You can watch the process from the left, as someone turns the crank slowly and shifts and you'll see what I'm talking about.
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  9. #9
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    Quote Originally Posted by RED5
    Odd, I've never seen a granny with a "pip" on it, but if you have then I'd guess you may have a point. Either way since granny rings don't have "ramps" or "gates" I still don't see how it matters.
    RF, Blackspire and even XTR grannies have the pips, but even odder, Blackspire SS rings have the pips.
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