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Thread: Anthem 2x9

  1. #1
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    Anthem 2x9

    I've got an old pair or RF Turbines laying around and I was thinking of trying to convert my anthem (not X) to a 2x9 setup. Not really concerned about weight, but I though I might achieve a narrower Q-factor than my current RF Dues w/ External BB.

    Anyone tried this? Any tips or issues you've run into. I was thinking of going 42t x 29/30t with a 108mm Isis BB. I'm concerned about arm and ring clearance as well as moving the FD down (if it will still clear the linkage assembly).

    Anyway, just thought if anyone had done this and how it turned out.

    Thanks!

  2. #2
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    I've been using a 2x9 44t/29t setup on the Anthem with an older Coda crankset using an XTR Octalink 112.5 mm bottom bracket for the past year. The cranks are 2x9 specific, so I am assuming that the spider was offset to achieve the best chainline. I am not sure what it would be like when using a spider meant for a triple.

    With this set up, I had to add a 2.5 mm spacer on the right side of the BB to move the crank outwards and keep the 44t ring from hitting the chainstay. It was necessary to achieve a sufficient gap between the chainring and the chainstay. It isn't much, but they don't touch when pedaling and don't touch over the range of motion of the rear suspension. On the flip side, chainsuck could really cause some damage.

    No issues with the small ring. No issues with the XTR 950 front derailleur either. Chainline is fine, and I have no issues with the shifting or the drivetrain. I am entertaining the thought of getting a 42t ring to give me just a little bit more clearance, but it isn't enough concern for me to act on it yet.

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    Thanks!

    I've got an old BB that's shot. Maybe I'll thread it in and out till it works and then measure to figure out the correct spindle length. I just hope is allows for the full range of gears.

  4. #4
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    I put a FSA 2X9 on my advanced xtc and i had to run 2 spacers on the drive side.With some bar tap on the frame im real close to hitting with the big ring.

  5. #5
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    jamone, good luck with this venture. I really want to put a 2 ring front crankset on, with a 41/29 or something similar. The choices right now that are easily available are middleburn duo and fsa kforce (way too much $$). I don't want to buy something until I can figure out if the chainring and crankarm clearance is there.

    If you do a mockup, please take pictures or measurements and share them with us.

  6. #6
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    743power, you can easily adjust the chainline for most cranksets - spacers for the ones with the integrated BBs, and a longer spindle with spacers for the older style cranksets.

  7. #7
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    I used a 73 x 113 isis bb and threaded it all the way into the 68mm anthem shell. This would give the chainline of a 68 x 108 bb (I think). The chain line was ~50mm, I thought it would be less than that. Maybe I was measuring wrong, I measured to the center of the two rings. The rings are 44/32. There was plenty of arm and chainring clearance. There would be even more with a 42 big ring. When the shock compresses the chainstay actually moves away from the chainring due to the meastro link extending.

    Looks like it should work!
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  8. #8
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    pic showing chainring clearance. q-factor was ~3/8" smaller than the dues w/ external bb
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  9. #9
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    Rotor makes a set of 27/40 rings for the 74/110 bolt pattern. I'm using their 2x9 cranks and the q-factor is significantly narrower than anything I've ever tried. Nice set of cranks and rings BTW.

  10. #10
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    Looks good Jamone. No real need to try out the 42t, it seems like you have plenty of clearance.

    If you need a lower gear, the smallest chainring that will fit on those Turbines should be a 29.

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    [quote=Jamone]pic showing chainring clearance. q-factor was ~3/8" smaller than the dues w/ external bb[/quote

    You're going to eventually use a 68x108mm BB, you were just testing it with the 113, right? So, when you say that the q-factor was 3/8" smaller, do you mean just on the drive-side, where you were mimicking the 108mm spacing, or from crankarm to crankarm mounted on the 113? I ask because I want to do this exact thing with an ISIS Race Face Next crankset, and I'm assuming the crankarm dimensions on those are the same as your Turbines, and that there will be enough chainstay/crankarm clearance.

    Edit: OK, I see you actually said there was crankarm clearance in the preceding post. I'm still curious about the q-factor, though.
    Last edited by perioeci; 03-04-2009 at 03:54 PM.

  12. #12
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    with the 113mm bb the total q-factor was ~3/8" less. With a 108 it'd be ~1/2"-5/8" less. Not too bad! Next I'll have to test out the chainline to see if all the gears are avaliable.

  13. #13
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    Quote Originally Posted by Jamone
    with the 113mm bb the total q-factor was ~3/8" less. With a 108 it'd be ~1/2"-5/8" less. Not too bad! Next I'll have to test out the chainline to see if all the gears are avaliable.
    Yeah, that sounds great. Please keep us posted.

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