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  1. #1
    dude!!! marcus987's Avatar
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    online gear ratio calculators?

    does any of you guys know any sites with gear ratio calculators on them?
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  2. #2
    freedom lika shoppingcart PunkGuy's Avatar
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    http://www.gsportbmx.co.uk/support/r...all_gears.html
    article on gearing

    from the site:
    "So let's compare a 44 tooth sprocket a 36 tooth sprocket and a 25 tooth sprocket.

    A 44 has a working radius of about 89mm so on a 180mm crank thatís almost bang on 1/2 way out. Therefore if you can press down with a force of 1000 Newtons (which you might well be capable of) the chain will have to take a load of around 2000 N.

    A 36 has a radius of about 72mm so on a 180mm crank the chain tension will be 180/72 x 1000 which is about 2500 Newtons.

    A 25 has a radius of only 50mm. With our 180mm crank we get a chain load of 3600 Newtons!

    So on a 25-9 gear set up the chain has to take nearly twice the tension of an old school 44-16."
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  3. #3
    Senior Member Brian's Avatar
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    So what does all that mean?

  4. #4
    I'm switching to quads racersk66's Avatar
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    Quote Originally Posted by Expatriate
    So what does all that mean?
    Thats what i want to know. I didn't pay attention in science in 7th grade to remember it.

  5. #5
    |+|+|+|+|+|+| * jack *'s Avatar
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  6. #6
    Senior Member Brian's Avatar
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    I busted a side plate on my chain with 180mm cranks and 39x16 gearing.

  7. #7
    Senior Member sxe fbm rider's Avatar
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    Iy your are just riding street or park or dirt bmx you dont need a gear ration calculator. There are the basic gear ratios. just pick one that you want.

  8. #8
    member
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    45,44,43-16
    39-14
    36-13
    33-12
    30-11
    28-10
    25-9

  9. #9
    dude!!! marcus987's Avatar
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    what would be better for park: 36-13 or 44-13. i'm just wondering because i've just got a bmx for park riding and its got 36-13 and somewhere i have a pretty decent 44 tooth sprocket.
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  10. #10
    dude!!! marcus987's Avatar
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    forget that last post, it dont matter any more.
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  11. #11
    Senior Member sxe fbm rider's Avatar
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    36-13 is just fine for park.

  12. #12
    dude!!! marcus987's Avatar
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    what would be better for dirt?
    39-16
    39-17
    39-18
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  13. #13
    Senior Member
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    39-16, but just get a 44t

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