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  1. #1
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    SIR 9 EBB crank position and chain length setup not easy

    Ok so I just picked up my first Niner bike - a medium 2009 SIR 9 SS.

    On my old SS, I ran the crank on the EBB between the 3 and 5 o'clock position looking at it from the drive side.

    The problem I'm having is setting up the chain at that EBB position to work with multiple cogs. I have it setup running 32/20, which works great with the cranks at 4 o' clock and the chain with a missing link.

    The problem is when trying to run a 32/19 or 32/18. Since the EBB is close to 3 o'clock (furthest length away from the rear cog), a smaller cog makes it impossible to tighten the chain without using a half link or removing links and running the EBB further back.

    I run 32/20 setup 90% of the time, so I prefer to keep the EBB at the 3 to 5 position. Anything between the 6 and 9 o'clock puts a lot of stress on my knees. Then I'll need a setback seatpost and/or the seat way back and I think the cockpit will feel long??

    Any advise? Use a half link? Run a 33 or 34 chainring with the 18 or 19 cog in order to keep the EBB in the 3 to 6 position all the time?

    I'm sort of stumped here. How do most of you set your's up? I'm leaning towards trying a 33t or 34t chainring. I don't think it will hit the frame, since it will be at the 3 o'clock, but didn't install it yet to verify.

  2. #2
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    When I change cogs, I just adjust the tension, I prefer to run mine between 9 and 3, I adjust my chain accordingly. It seems like you are thinking to hard about it. I run a 34x18 most of the time but it can range from 18 - 21t.

  3. #3
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    I think you are expecting too much from your EBB.

    Either use a half link as you suggested or accept the variation in the relationship between your pedal and saddle.

    If you are experiencing knee strain you may be pedalling seated at too low a cadence when you should be standing and driving your pedals down from the hips.

    Once I have set my EBB and saddle I have never bothered to adjust the saddle to compensate for changes in the EBB position over time.

  4. #4
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    What I've found is that I only need to adjust my seat height when I make that sort of change to the EBB. It works because when you raise the seat, you're moving the saddle back at the same time, so in most cases, that's enough to keep it feeling "right," and it's subtle enough to not cause issues with reach.

    Have you tried measuring your seat height & setback when the EBB is where you like it vs. in the position that's giving you trouble?
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  5. #5
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    Consider keeping a second chain around, cut with a half link if needed. When you want to change gears, toss it on there. If you size it right, you will not have to move your EBB much at all.

  6. #6
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    Thanks for the advice. I didn't even think about a second chain option, which I do have. I'll keep playing around with it until it feels right. I think I'm expecting too much from this EBB.

  7. #7
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    SIR 9 EBB crank position and chain length setup not easy

    I assumed you would be swapping chains when you swapped cogs. Otherwise your suggestion from your OP makes sense. Keep the tooth count the same on your second combo and chain length and EBB position should stay virtually the same. eg 33/19 to raise your gearing compared to 32/20. It does mean the hassle of changing a chain ring each time though.

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