Sprocket/RPM ratio question......LOOK!!!!
02-23-2006, 01:17 AM
#1
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Sprocket/RPM ratio question......LOOK!!!!
Okay, everyone knows that for every -1 tooth in the front sprocket is about the same as adding +3 teeth to the rear sprocket......
Let say you have two (2) of the SAME EXACT bikes....hmmm lets say F4i's.
Bike one: is geared -1 front, and +5 rear.
Bike two: is geared stock front, and +8 rear.
These two bikes have diffrent physical gears, But the outcome of the gearing is still comprobable to one another. (b/c -1 is pretty close to adding +3 in the rear)
Here's my question: Will the diffrent gearing have an effect on the bikes given RPM at a given speed? Ex. Both bikes geared as I stated and are doing 45mph, will the bikes be at the same RPM or diffrent?
Let say you have two (2) of the SAME EXACT bikes....hmmm lets say F4i's.
Bike one: is geared -1 front, and +5 rear.
Bike two: is geared stock front, and +8 rear.
These two bikes have diffrent physical gears, But the outcome of the gearing is still comprobable to one another. (b/c -1 is pretty close to adding +3 in the rear)
Here's my question: Will the diffrent gearing have an effect on the bikes given RPM at a given speed? Ex. Both bikes geared as I stated and are doing 45mph, will the bikes be at the same RPM or diffrent?
02-23-2006, 11:28 AM
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Re: Sprocket/RPM ratio question......LOOK!!!!
Originally Posted by Tdeal28
Okay, everyone knows that for every -1 tooth in the front sprocket is about the same as adding +3 teeth to the rear sprocket......
Let say you have two (2) of the SAME EXACT bikes....hmmm lets say F4i's.
Bike one: is geared -1 front, and +5 rear.
Bike two: is geared stock front, and +8 rear.
These two bikes have diffrent physical gears, But the outcome of the gearing is still comprobable to one another. (b/c -1 is pretty close to adding +3 in the rear)
Here's my question: Will the diffrent gearing have an effect on the bikes given RPM at a given speed? Ex. Both bikes geared as I stated and are doing 45mph, will the bikes be at the same RPM or diffrent?
Let say you have two (2) of the SAME EXACT bikes....hmmm lets say F4i's.
Bike one: is geared -1 front, and +5 rear.
Bike two: is geared stock front, and +8 rear.
These two bikes have diffrent physical gears, But the outcome of the gearing is still comprobable to one another. (b/c -1 is pretty close to adding +3 in the rear)
Here's my question: Will the diffrent gearing have an effect on the bikes given RPM at a given speed? Ex. Both bikes geared as I stated and are doing 45mph, will the bikes be at the same RPM or diffrent?
Some people will tell you otherwise but those are the people that didnt pay attention in high school physics and didnt take physics in college.
02-23-2006, 12:05 PM
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Re: Sprocket/RPM ratio question......LOOK!!!!
Originally Posted by MikeM
Its the same.
Some people will tell you otherwise but those are the people that didnt pay attention in high school physics and didnt take physics in college.
Some people will tell you otherwise but those are the people that didnt pay attention in high school physics and didnt take physics in college.
02-23-2006, 05:11 PM
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Re: Sprocket/RPM ratio question......LOOK!!!!
Okay, Now will one bike be "Smoother" as far as throttle input goes vs. the other?
I am just trying to figure out if there really is a diffrence to going with a -1 front or making up the diffrence off the -1 front with a 3 tooth larger sprocket in the rear......
The only two diffrences I could possibly think of would be the RPM thing and maybe the twitchyness/smoothness off the gearing....
I am just trying to figure out if there really is a diffrence to going with a -1 front or making up the diffrence off the -1 front with a 3 tooth larger sprocket in the rear......
The only two diffrences I could possibly think of would be the RPM thing and maybe the twitchyness/smoothness off the gearing....
02-24-2006, 07:58 AM
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Re: Sprocket/RPM ratio question......LOOK!!!!
Originally Posted by Tdeal28
Okay, Now will one bike be "Smoother" as far as throttle input goes vs. the other?
I am just trying to figure out if there really is a diffrence to going with a -1 front or making up the diffrence off the -1 front with a 3 tooth larger sprocket in the rear......
The only two diffrences I could possibly think of would be the RPM thing and maybe the twitchyness/smoothness off the gearing....
I am just trying to figure out if there really is a diffrence to going with a -1 front or making up the diffrence off the -1 front with a 3 tooth larger sprocket in the rear......
The only two diffrences I could possibly think of would be the RPM thing and maybe the twitchyness/smoothness off the gearing....
No, they will be the same bike. You can not tell the difference between the two.
02-24-2006, 04:16 PM
#10
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Re: Sprocket/RPM ratio question......LOOK!!!!
Originally Posted by MikeM
Its the same.
Some people will tell you otherwise but those are the people that didnt pay attention in high school physics and didnt take physics in college.
Some people will tell you otherwise but those are the people that didnt pay attention in high school physics and didnt take physics in college.
mr. m is correct
02-24-2006, 04:23 PM
#11
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Re: Sprocket/RPM ratio question......LOOK!!!!
the main thing to consider in gearing is the ratio. that is back sprocket divided by front sprocket. for example a 45 15 combo results in a 3 to 1 ratio. a 48, 16 combo results in the same 3 to 1 ratio. this means that with either combo with every three front gear revolutions the wheel will turn once. therefore they will run the same speeds at the same RPMS.
the front sprocket teeth equaling 3 rear sprocket teeth is a rule of thumb. it is not always acurate, but its pretty close. this is because most bikes run near 3 to 1 ratio stock.
there is also the minor considerations of overall mass and rotating mass. a smaller front and smaller rear will weigh less( but very little). the will also have different rotating masses and this can change torque transfer(smoothness). I would completely ignore this however because the difference would be something like 0.05 tooth difference on a sprocket.
Chain wear should also be considered. going smaller in the front will cause increased chain wear because of the tighter radius. so as long as going up more in the back does not requre a much more expensive chain it is cheaper in the long run to go with stock sized front sprockets.
by the way 2 four year degrees and working on my Phd.
the front sprocket teeth equaling 3 rear sprocket teeth is a rule of thumb. it is not always acurate, but its pretty close. this is because most bikes run near 3 to 1 ratio stock.
there is also the minor considerations of overall mass and rotating mass. a smaller front and smaller rear will weigh less( but very little). the will also have different rotating masses and this can change torque transfer(smoothness). I would completely ignore this however because the difference would be something like 0.05 tooth difference on a sprocket.
Chain wear should also be considered. going smaller in the front will cause increased chain wear because of the tighter radius. so as long as going up more in the back does not requre a much more expensive chain it is cheaper in the long run to go with stock sized front sprockets.
by the way 2 four year degrees and working on my Phd.
02-24-2006, 04:26 PM
#12
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Re: Sprocket/RPM ratio question......LOOK!!!!
the larger rear on the other bike makes up for the front so it still has to spin faster...
it's just math... the final drive ratio is the same, dosent matter how you get it that way.
it's just math... the final drive ratio is the same, dosent matter how you get it that way.
02-24-2006, 07:07 PM
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Re: Sprocket/RPM ratio question......LOOK!!!!
Originally Posted by ripley311
Chain wear should also be considered. going smaller in the front will cause increased chain wear because of the tighter radius. so as long as going up more in the back does not requre a much more expensive chain it is cheaper in the long run to go with stock sized front sprockets.
This was the main reason why I was just going to go with a 3 tooth bigger sprocket in the rear instead of going with a -1 front. After I was thinking about it I thought maybe there might be a few other slight diffrences....
EVERYONE.....check this site out (if you ride an F4i)
You can put in diffrent sprocket ratio's and change the wheel/tire/final drive ratio of the tranny ect to compare a 100% stock F4i vs. a F4i that just has a gearing change or more. It will tell you how much Torque you gain by the sprocket change and an estimated top speed for each gear....Stock vs. Geared...
http://jesture.com/misc/f4igearingform.php
03-13-2006, 09:29 PM
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Re: Sprocket/RPM ratio question......LOOK!!!!
ok after reading this it makes me wounder at what point in gearing, lets say changing the front and rear from stock will make second gear after changing the gearing the same as 1st gear was when stock?
03-15-2006, 03:12 PM
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Re: Sprocket/RPM ratio question......LOOK!!!!
Originally Posted by Holmes
I got a f4 and want to gaear it for slow stunts. anyone know what would be a good size?
03-16-2006, 12:09 PM
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Re: Sprocket/RPM ratio question......LOOK!!!!
Originally Posted by Holmes
yeah but then i would have to clutch the hell out of it from a stop to get it up its only a 600
03-17-2006, 05:41 PM
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Re: Sprocket/RPM ratio question......LOOK!!!!
Originally Posted by fmf400ex03
ok after reading this it makes me wounder at what point in gearing, lets say changing the front and rear from stock will make second gear after changing the gearing the same as 1st gear was when stock?
