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Old 10-26-05, 11:40 AM   #1
marcus987
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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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Old 10-26-05, 11:48 AM   #2
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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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Old 10-26-05, 03:38 PM   #3
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So what does all that mean?
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Old 10-26-05, 03:53 PM   #4
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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.
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Old 10-26-05, 03:56 PM   #5
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http://sheldonbrown.com/gears/
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Old 10-26-05, 04:03 PM   #6
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I busted a side plate on my chain with 180mm cranks and 39x16 gearing.
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Old 10-27-05, 11:32 AM   #7
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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.
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Old 10-27-05, 01:34 PM   #8
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45,44,43-16
39-14
36-13
33-12
30-11
28-10
25-9
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Old 10-27-05, 02:13 PM   #9
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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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Old 10-27-05, 02:15 PM   #10
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forget that last post, it dont matter any more.
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Old 10-27-05, 07:38 PM   #11
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36-13 is just fine for park.
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Old 10-28-05, 01:50 PM   #12
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what would be better for dirt?
39-16
39-17
39-18
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Old 10-28-05, 09:03 PM   #13
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39-16, but just get a 44t
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