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  1. #1
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    Need help comparing geometry numbers

    Hi all,
    Looking at possibly getting a new frame. I currently ride a niner air 9 scandium, size med. I love the geometry but want to upgrade to a carbon frame. I would love to purchase the air 9 carbon, but I cant justify the price. Not yet anyways. My problem is beyond ett I do not understand how the different geometry effects handling and fit.
    Here is the geo of my med air 9 in inches

    ETT/SeatTube/WheelBase/Headtube angle/Headtube length/seat tubeangl/chainstay
    23.9----16.5--------43.1------------71.1-------------------4.3---------------------73--------------17.3


    24-------19.5--------43.4------------70.5-------------------3.9---------------------73--------------17.3

    Bike #1 is niner air 9

    Bike #2 is santa cruz high ball

    The main diff. i can see is the seat tube. On my niner I run a lot of seat post. More then 3 in difference between the bikes. With the other numbers being so close together would I just be able to run my post 3in shorter to compensate for the difference?

    Thanks Ben

  2. #2
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    Reputation: kenbentit's Avatar
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    While the ST length is quite a bit different that measurement isn't going to have nearly as much effect as the Head Angle. Slacker HA's equate to a more relaxed feel and stability at speed and on steep sections. It also means slower steering and requires a more forward position while climbing in order to keep the front end down. Those are the "extreme" examples though, not what you're likely to experience with either of those bikes (70.5 deg isn't really all that slack, 64 deg is ). Running the post lower may be all you need to do to get the bike to fit you but it's a good idea to check into what the max. insertion is on the seat tube. Quite often the ST will have a slight bend or even a weld penetration that prevents the post from going all the way inside. Welds won't be an issue with carbon but there will most likely be some sort of plug in there from the molding process. Beyond that, the longer wheel base will give stability but make cornering a bit tougher (again, Min/Max examples). The Seat Tube Angle is important since it will affect your ETT but both bikes are the same so you should be OK there.
    Desert Sunset Calls/Upward, Pain, Perseverance/Welcome Solitude

  3. #3
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    Thanks Ken, I appreciate the feedback.

  4. #4
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    Reputation: Ryder1's Avatar
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    Understanding geometry/fit is a complex issue but the size and geometry of those two bikes is extremely similar and looks like a good swap as long as the High Ball's standover isn't too high for your balls. Height of the bottom bracket is another number to consider but they're also very similar on those two bikes.
    ride natty ride

  5. #5
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    No problem man! I'd highly recommend getting out to any demo events you can and trying a wide range of bikes. That'll give you a better feel for how much a small change in geo. numbers can have on the ride quality of the bike. Fit & feel are a VERY individualized thing so it's good to know what you really like before you drop a big chunk of $$.
    Desert Sunset Calls/Upward, Pain, Perseverance/Welcome Solitude

  6. #6
    drink coffee, ride.
    Reputation: cookiedough's Avatar
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    Can't agree more with ken's suggestion - get out and demo! A friend and I, (iammemares) did quite a few demos while comparing them to our current setups. Crazy thing is, we ended up on the same frame, just different size. He is 1" shorter than I. He rides a RIP9 small, with setback seatpost and longer stem and wide bars. I ride a med with 50mm stem, narrower bars and straight post. Our cockpit measurements are nearly identical, but the bikes' handle and "feel" quite different, each accentuating the particular characteristic we each prize, which is not the same.

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