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  1. #1
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    gear ratio thoughts

    read today that due to wheel size a 29" in the 24x36 position (granny) is equivalent to a 26" in 24x28 (roughly 3rd from highest in back). the article also stated that the 29er in other equivalent gears is 15 % faster than a 26" at the same rpm. this would explain alot when it comes to my riding vs my friends on 26ers e.g. equal to slower on +15% grade climbs and much faster than most as the grade decreases.

    input?

  2. #2
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    Quote Originally Posted by LB412 View Post
    read today that due to wheel size a 29" in the 24x36 position (granny) is equivalent to a 26" in 24x28 (roughly 3rd from highest in back). the article also stated that the 29er in other equivalent gears is 15 % faster than a 26" at the same rpm. this would explain alot when it comes to my riding vs my friends on 26ers e.g. equal to slower on +15% grade climbs and much faster than most as the grade decreases.

    No they just push a higher gear & go the same speed.

    input?
    No they just push a higher gear & go the same speed.

  3. #3
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    Nominally, it is a 12% difference in diameter. So a 36 tooth rear cog is the same relative diameter as a 32 on 26". I think somebody got screwed up between the area of the wheel and the diameter. Area is exponential but diameter is just a ratio.

  4. #4
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    Quote Originally Posted by bulerias View Post
    Nominally, it is a 12% difference in diameter. So a 36 tooth rear cog is the same relative diameter as a 32 on 26". I think somebody got screwed up between the area of the wheel and the diameter. Area is exponential but diameter is just a ratio.
    That's right but a 33t on the 26 wheel is actually the closest match to the the 29'ers 36t. A gear inch chart is the easiest way to compare gearing between different wheel sizes.



    Quote Originally Posted by muzzanic View Post
    No they just push a higher gear & go the same speed.
    I know what you mean but actually they push the exact same gear to go the same speed. One rider on a 26 wheel bike and another on a 29er riding side by side at identical speed and identical cadences will be using different cog/chainring combos but will be riding in the same gear because wheel size is one of the three factors in determining gearing.

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    Quote Originally Posted by J.B. Weld View Post
    That's right but a 33t on the 26 wheel is actually the closest match to the the 29'ers 36t. A gear inch chart is the easiest way to compare gearing between different wheel sizes.





    I know what you mean but actually they push the exact same gear to go the same speed. One rider on a 26 wheel bike and another on a 29er riding side by side at identical speed and identical cadences will be using different cog/chainring combos but will be riding in the same gear because wheel size is one of the three factors in determining gearing.
    You don't see a lot of 33 tooth cassette cogs tho. Nominally it would be 32.3 teeth but a 29" wheel is really only about 28.5 which makes 32.85 so you're right. The point was that it was nowhere near 28 teeth.

  6. #6
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    Quote Originally Posted by J.B. Weld View Post
    I know what you mean but actually they push the exact same gear to go the same speed. One rider on a 26 wheel bike and another on a 29er riding side by side at identical speed and identical cadences will be using different cog/chainring combos but will be riding in the same gear because wheel size is one of the three factors in determining gearing.
    You are right but I was trying to make it easyer for the OP to understand.

    Because they ahe using a higher gear on the cassette.

  7. #7
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    Quote Originally Posted by LB412 View Post
    read today that due to wheel size a 29" in the 24x36 position (granny) is equivalent to a 26" in 24x28 (roughly 3rd from highest in back). the article also stated that the 29er in other equivalent gears is 15 % faster than a 26" at the same rpm. this would explain alot when it comes to my riding vs my friends on 26ers e.g. equal to slower on +15% grade climbs and much faster than most as the grade decreases.

    input?
    The power of the engine is what determines the speed.

    29ers are typically geared a little lower so that the gear inches fall into the same range as a 26er.

    If you ride a 29er with 26er gearing, though, you will either just get stronger or you will end up downshifting a lot.

    -F
    It's never easier - you just go faster.

  8. #8
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    It's really only the Granny gear I question as it is the difference maker on the steepest of climbs (for this engine)... Sounds like you confirmed that it is more difficult but not to the level I first thought.... 24x33 vs. 24x28.

  9. #9
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    32x18 29er = 32x16 26er
    A Useful Bear is a handy thing.

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    Quote Originally Posted by bsieb View Post
    32x18 29er = 32x16 26er
    Makes sense as the difference should flow through all gear combos.

  11. #11
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    Sounds like Shimano feels there is a need:

    2014 Shimano: 29"er Friendly- 27.5"er Intros, New Deore Group

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    22-36 27.5" is almost exactly 22-34 26" EWD. 22-36 on a 29er is still a full 1" bigger EWD than 22-34 26" so they're still ignoring 29er climbing capability.

  13. #13
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    gear ratio thoughts

    great link for easy gear ratio calcs:


    Mountain Bike Gear Ratio Calculator V4.0


    "I ride my bike to ride my bike"- Zen proverb

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  14. #14
    dwt
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    gear ratio thoughts

    Quote Originally Posted by LB412 View Post
    Sounds like Shimano feels there is a need:

    2014 Shimano: 29"er Friendly- 27.5"er Intros, New Deore Group
    I predict the crankset will be standard equipment on 29'ers sold in 2014, just as compact chainrings (50-34T)are now standard on road bikes. More bike consumers of average ability than hammerheads out there.




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