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  1. #1
    mtbr member
    Reputation: SeaBass_'s Avatar
    Join Date
    Apr 2006

    SIR9 sizing and crank length.

    2 questions for the SIR9 crowd.

    I'm 6'3 with 34" inseam - Currently riding a 21" Dambala with 120mm stem & FuBars, 180mm XT cranks, and a setback seatpost.

    Would I be better off with the Large or X-Large SIR9 frame?

    Anybody encounter foot strike or ground clearance issues with 180mm cranks on the SIR9?

    Thanks for your help!

  2. #2
    Phatt Tire Luva'
    Reputation: Qanuk's Avatar
    Join Date
    Jan 2006
    I ride an XL EMD - quassi SS these days (very similar in geometry, in fact I'm pretty sure the top tubes are the same length... the top tube length is "the" most important component of proper frame fit). I'm planning on building a SIR in the next several months, and it too will absolutely be an XL. I will say that I am slightly disproportionate in torso/leg length, but regardless I'm still 6'1" w/34'' inseam. Quite honestly I can't see how you could possibly take anything other than an XL. Now with that said, I'm a very firm believer on proper bike fit & biomechanics... but still I'd say there is about a 0.01% chance that what ever build/body proportions you have going on, you'd be a size L frame.

    As for 180mm cranks... I ride with a 175mm now, but will most likely be going to a 180mm on the new build. With that said, I can tell you that was one of the things that I had really thought the exact opposite of what actually occurs - would have been the case. I would have thought I'd end up with greater ground clearance than the ol' 26" bike, but I absolutely get more rock hits since I've been on my Niner. Quite honestly - it is something that you'll likely only notice for the first few rides, at which point it will become the new norm... and you'll quickly build a new ridging style - when needed, to cope. Also of note is that you'll always have the option of adjusting the EBB from the 12 o'clock position - to increase the maximal ground/obstacle clearance for the crank arm.

    If you need more info on frame sizing shoot me a PM.

    Hope that helps!



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  3. #3
    Mtbr Forum Sponsor - Homebrewed Components
    Join Date
    Jul 2006
    you'll have about 8 feet of seat post sticking out of a large, give or take 7 feet.

    I also have a 34" inseam (well, 34.5"), and i've broken 3 different large frames, all within about a year's time, and all at the seat tube/top tube weld. There's just too much leverage on the frame with that much post sticking out.
    basically what i'm getting at is get an xl.

  4. #4
    mtbr member
    Reputation: SeaBass_'s Avatar
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    Apr 2006
    Thanks all! The advice is much appreciated. Looks like an XL for me.

  5. #5
    mtbr member
    Reputation: idaz's Avatar
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    Nov 2007
    I'm 6'2" and about a 34" pant inseam as well. I'm on a 1st generation L SIR with 180 cranks.
    ISAR's point about excessive seatpost being an effective lever against the frame rings true. I've got small crack developing there. Otherwise the frame fits me well with a 100mm stem.
    If you're on rocky trails you will get a few more pedal strikes initially with the 180s. That disappears quickly as you learn to time your stroke.

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