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  1. #1
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    Stem help please

    I just picked up a used SIR 9 medium frame and swapped all my parts over from a XXIX SS. I should have it done this week and after a few rides I'll tweak the stem length, spacer height, and seat position and height.

    I'm 5"10" to 5'11". I ran a 90mm +6 stem, Niner flat bars, and Reba 100mm fork that I transferred over to the SIR 9.

    My questions are:

    Is a 90mm stem a good starting length? The Niner website shows their stems in the negative position. Are they meant to be run negative?

    I looked through the SIR 9 photo posts and most run straight seatposts instead of setback. Anyone swap between the two?

  2. #2
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    If it makes the fit better, then go for it. You can run a 120mm stem if you wanted to, in the positive or negative angle...it's not gonna hurt the bike. Same with seat posts, if you can't get your saddle far enough back on a straight post, then the only option would be to either to adjust your stem/bar positioning...or use a setback post. It seems like a lot of the OE setups provide a 90mm stem and straight post as a starting point, any changes beyond that are completely personal preference. If you have too much weight in the rear when climbing, your front tire may start to lift or get off course.

    I used to run a setback post, but realized that where my saddle was positioned, I could get the same fit with a straight post. Straight posts are more readily available, and some of the weight wheenie posts don't offer setback versions. Probably one reason why you don't see them on a lot of bikes. In the end, if it works for you, then give it a try. Worst thing that will happen is it doesn't feel right, and you tweak the fit.

  3. #3
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    Quote Originally Posted by drz400sm View Post
    If it makes the fit better, then go for it. You can run a 120mm stem if you wanted to, in the positive or negative angle...it's not gonna hurt the bike. Same with seat posts, if you can't get your saddle far enough back on a straight post, then the only option would be to either to adjust your stem/bar positioning...or use a setback post. It seems like a lot of the OE setups provide a 90mm stem and straight post as a starting point, any changes beyond that are completely personal preference. If you have too much weight in the rear when climbing, your front tire may start to lift or get off course.

    I used to run a setback post, but realized that where my saddle was positioned, I could get the same fit with a straight post. Straight posts are more readily available, and some of the weight wheenie posts don't offer setback versions. Probably one reason why you don't see them on a lot of bikes. In the end, if it works for you, then give it a try. Worst thing that will happen is it doesn't feel right, and you tweak the fit.

    Well said. I agree and that's always been my philosophy. It just confused me why Niner is showing their stems running negative.

  4. #4
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    Quote Originally Posted by jsvwx View Post
    Well said. I agree and that's always been my philosophy. It just confused me why Niner is showing their stems running negative.
    A lot of us run stems in the negative position which tends to increase the reach by a bit. For instance, my 105mm stem in the negative position gives me 7mm more reach. Now that's not the only solution. Positive, negative or even a 0 degree stem are all simple plumbing to get the bar in the position best suited to your fit and riding needs. Combine spacers, steerer tube length, front tire size, amount of travel in the front fork, riser bars, flat bars or even negative rise bars all added together provide the plumbing to get the bars where you need it.

    You probably see more stems flipped negative in the smaller 29"er sizes in an effort to get the bars down to or even below the saddle height. On the Large and X-Large sizes, guys legs are so long that the saddle tends to go up quite a bit meaning that to get the bars equal to or above saddle height - some plumbing is going to be required including running the stem in positive position.

  5. #5
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    Stem help please

    Quote Originally Posted by jsvwx View Post
    Well said. I agree and that's always been my philosophy. It just confused me why Niner is showing their stems running negative.
    Bar height. A negative rise stem lets you get the bar lower. Especially important for smaller riders, or any rise that likes a low aggressive position.
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  6. #6
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    Stem help please

    Quote Originally Posted by BruceBrown View Post
    A lot of us run stems in the negative position which tends to increase the reach by a bit. For instance, my 105mm stem in the negative position gives me 7mm more reach. Now that's not the only solution. Positive, negative or even a 0 degree stem are all simple plumbing to get the bar in the position best suited to your fit and riding needs. Combine spacers, steerer tube length, front tire size, amount of travel in the front fork, riser bars, flat bars or even negative rise bars all added together provide the plumbing to get the bars where you need it.

    You probably see more stems flipped negative in the smaller 29"er sizes in an effort to get the bars down to or even below the saddle height. On the Large and X-Large sizes, guys legs are so long that the saddle tends to go up quite a bit meaning that to get the bars equal to or above saddle height - some plumbing is going to be required including running the stem in positive position.
    The reach increases only if you do not keep the bar at the same height (add spacers under the stem). Flip the stem down, no spacers, and the reach increases and a
    The bar is lower.
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  7. #7
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    Quote Originally Posted by shiggy View Post
    The reach increases only if you do not keep the bar at the same height (add spacers under the stem). Flip the stem down, no spacers, and the reach increases and a
    The bar is lower.
    Hmmm. If I plug in my numbers at the stem comparison tool: Stem Comparison Tool | yojimg.net

    All things being equal for at least one of my bikes - say 15mm of spacers, 72 degree head angle, 105mm stem length (reach) and compare the same set up with the same stem flipped negative and then positive - the one with the negative (-6 degree) stem says it will have 7mm more reach and be 21mm lower than if I flip the same exact stem positive (using the same spacers, head angle and bars). In that case, I didn't change the spacers, but the simple flip of the stem will change the reach as well as the height. I get the same reading if I use 0 spacers and simply flip the stem from negative to positive (which will, of course, raise/lower the bar).

    Am I reading that wrong?

    STEM

  8. #8
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    Stem help please

    Quote Originally Posted by BruceBrown View Post
    Hmmm. If I plug in my numbers at the stem comparison tool: Stem Comparison Tool | yojimg.net

    All things being equal for at least one of my bikes - say 15mm of spacers, 72 degree head angle, 105mm stem length (reach) and compare the same set up with the same stem flipped negative and then positive - the one with the negative (-6 degree) stem says it will have 7mm more reach and be 21mm lower than if I flip the same exact stem positive (using the same spacers, head angle and bars). In that case, I didn't change the spacers, but the simple flip of the stem will change the reach as well as the height. I get the same reading if I use 0 spacers and simply flip the stem from negative to positive (which will, of course, raise/lower the bar).

    Am I reading that wrong?

    <a href="http://www.flickr.com/photos/7166535@N05/8466690904/" title="STEM by BBcamerata, on Flickr"><img src="http://farm9.staticflickr.com/8377/8466690904_7aacdf7561_c.jpg" width="800" height="459" alt="STEM"></a>
    The image you show has different bar heights. With the same stem, if spacers are used to maintain the same bar height, the reach will not change when the stem is flipped, somewhat dependent on the stem clamp stack height.

    ...and I do not really trust those calculators because clamp stack height is rarely considered.
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