Sprocket changes and gearing
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To compensate for larger tires on the rear (20's), you should probably drop a tooth off of your front sprocket.
A smaller front sprocket adjusts the gearing in the same direction as a larger rear sprocket.
Front sprocket adjustments have more of an effect.
A smaller front sprocket adjusts the gearing in the same direction as a larger rear sprocket.
Front sprocket adjustments have more of an effect.
Lou, you can calculate the gear ratios...
Factory gearing is 14T front sprocket and 36T rear: 36/14=2.57 (any number bigger is geared lower and any number smaller is geared higher)
If you drop a tooth on the front: 36/13=2.77 (dropping teeth on the front lowers gear ratio)
If you raise a tooth on the back: 37/14=2.64 (adding teeth on the back lowers gear ratio)
If you add a tooth on the front: 36/15=2.4 (adding teeth on the front raises the gear ratio)
If you drop a tooth on the rear: 35/14=2.5 (dropping teeth on the rar raises the gear ratio)
It is commonly accepted that one tooth change on the front sprocket equals three on the rear sprocket...let's test it out:
If you drop a tooth on the front: 36/13=2.77
If you add 3 teeth to the rear: 39/14=2.79
Pretty close...
Hmm, now, how did changing your tires affect everything? Taller tires raise your gear ratio and shorter tires lower it...
Here is a sample calculator for your tire changes...
Find new gear ratio with new tire size calc
Your old tires were 18" tall, your new tires are 20" tall, your factory gear ratio is 2.57...according to the calculator you will need a gear ratio of 2.86 to have the same ratio with your new tires as the bike had stock...which would be a 13T front and a 37T rear...37/13=2.85.
Does this make sense?
Edit:
I wanted to add this to the thread:
I do not know how many of you have seen this but it is a very nice calculator built by 86atc250r from .org...Gabe is his name. Also, FYI, read the notes on the bottom of the calc...you can change tire height to roll out instead, etc.
He has the LTR in their now...
http://www.xcracing.com/gabe/quad_calc.exe
Factory gearing is 14T front sprocket and 36T rear: 36/14=2.57 (any number bigger is geared lower and any number smaller is geared higher)
If you drop a tooth on the front: 36/13=2.77 (dropping teeth on the front lowers gear ratio)
If you raise a tooth on the back: 37/14=2.64 (adding teeth on the back lowers gear ratio)
If you add a tooth on the front: 36/15=2.4 (adding teeth on the front raises the gear ratio)
If you drop a tooth on the rear: 35/14=2.5 (dropping teeth on the rar raises the gear ratio)
It is commonly accepted that one tooth change on the front sprocket equals three on the rear sprocket...let's test it out:
If you drop a tooth on the front: 36/13=2.77
If you add 3 teeth to the rear: 39/14=2.79
Pretty close...
Hmm, now, how did changing your tires affect everything? Taller tires raise your gear ratio and shorter tires lower it...
Here is a sample calculator for your tire changes...
Find new gear ratio with new tire size calc
Your old tires were 18" tall, your new tires are 20" tall, your factory gear ratio is 2.57...according to the calculator you will need a gear ratio of 2.86 to have the same ratio with your new tires as the bike had stock...which would be a 13T front and a 37T rear...37/13=2.85.
Does this make sense?
Edit:
I wanted to add this to the thread:
I do not know how many of you have seen this but it is a very nice calculator built by 86atc250r from .org...Gabe is his name. Also, FYI, read the notes on the bottom of the calc...you can change tire height to roll out instead, etc.
He has the LTR in their now...
http://www.xcracing.com/gabe/quad_calc.exe
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WOW Thats kicks butt!!! I have always wondered how to figure that!!! Thanks so much for the info OKTRX450R! I will be printing this off!!
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Especially since he spelled sprocket right and you didn't.......................... :smiley_1poke:
!!!!!!
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So much for my cowbell theory...
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OK all I guess im an idiot........im looking fo a pretty agressive mud tire. I had a set of MAXXIS Sur Track on my 300EX and loved them......however the smallest I can buy is 22" so by the calc I need to run a 14f and a 44r gearing......WOW.......not sure i want to do that.........So do you all have any suggestions for a 20" mud tire? Its all rocks mud/dirt where I ride mostly..... but i dont want to have to spend 1/2 a day to get ready to go to the dunes just to get the tires/gearing right.
thanks so much all!
thanks so much all!
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315 Posts
who makes good sprockets for the ltr?
Guys, remember the above theory for gearing is just that...a theory! I have 3 sets of 21" tall tires and none of them actually measure 21"! Also, rim width, yada, yada, will also make a difference. When you use the above information measure your factory tires actual height and measure your new tires actual height to get you a little closer...
ltrdude216---IMO take your pick. I ride sand and I try and avoid aluminum sprockets because they deteriorate too quickly. I own sunstar, moose, tag, sidewinder, and Tusk sprockets...none have failed nor worn extremely quick. If you have the money to spend the sidewinders with a DID X-ring chain should provide a very durable solution but mucho bucks. Sunstars are my current favorite as a front is $13 at my dealer and a rear $35. I have a 13T sunstar on my TRX I have been running since December 04!
rkboyer911---I do not think I would personally try and get back to factory gearing...IMO the LTR is geared really low from the factory. When I ride with the stockers I do not use 1st gear at all...start and stop in 2nd. It takes maybe 30 minutes (going really slowly) to change front and rear sprockets if you decide...maybe consider getting a 21" dune tire so your gearing is pretty close already to your mud bog tires.
Lou---IMO there is no drag gearing, hill climb gearing, etc, that works for everyone. First you have to look at your tires, their height, do you want to start in 1st, 2nd, or 3rd off the line? Are you bogging out of the hole? The only true answer is your personal experience and trying different combos out.
With 21" 6 paddle Extremes our LTR rides completely different then with 21" SSK I comp cuts...the same sprockets are completely different between the 2 tires.
ltrdude216---IMO take your pick. I ride sand and I try and avoid aluminum sprockets because they deteriorate too quickly. I own sunstar, moose, tag, sidewinder, and Tusk sprockets...none have failed nor worn extremely quick. If you have the money to spend the sidewinders with a DID X-ring chain should provide a very durable solution but mucho bucks. Sunstars are my current favorite as a front is $13 at my dealer and a rear $35. I have a 13T sunstar on my TRX I have been running since December 04!
rkboyer911---I do not think I would personally try and get back to factory gearing...IMO the LTR is geared really low from the factory. When I ride with the stockers I do not use 1st gear at all...start and stop in 2nd. It takes maybe 30 minutes (going really slowly) to change front and rear sprockets if you decide...maybe consider getting a 21" dune tire so your gearing is pretty close already to your mud bog tires.
Lou---IMO there is no drag gearing, hill climb gearing, etc, that works for everyone. First you have to look at your tires, their height, do you want to start in 1st, 2nd, or 3rd off the line? Are you bogging out of the hole? The only true answer is your personal experience and trying different combos out.
With 21" 6 paddle Extremes our LTR rides completely different then with 21" SSK I comp cuts...the same sprockets are completely different between the 2 tires.
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315 Posts
thanks for the quick reply
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75 Posts
well id just leave it becuase i put a 15 front on mine with stock tires and it pulled it just fine so if i was u id just leave the gearing it just depends if you want torque or speed
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so it sounds like a 13T would be an ideal set up for an mx track.?.?.? I havent raced on an mx track for more than a couple of months so im pretty green as to proper gearing set ups for mx tracks
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12? Holy crap man
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